ad5791 offload #2616

ahaslam2 · 2024-10-15T15:04:43Z

spi offload support for ad57xx dac

This adds offload support for the ad57xx dac to be able to send samples up to 1MSPS.

PR Type

Bug fix (a change that fixes an issue)
New feature (a change that adds new functionality)
Breaking change (a change that affects other repos or cause CIs to fail)

PR Checklist

I have conducted a self-review of my own code changes
I have tested the changes on the relevant hardware
I have updated the documentation outside this repo accordingly (if there is the case)

nunojsa

Here it goes my review. Note that I'm expecting some stuff to be sent upstream (like gpio reset)... Also it seems this driver could use a proper refactor if you are willing to do that 😄

nunojsa · 2024-10-16T11:25:55Z

drivers/iio/dac/ad5791.c

+	st->gpio_ldac = devm_gpiod_get_optional(&spi->dev, "ldac",
+						  GPIOD_OUT_LOW);
+	if (IS_ERR(st->gpio_ldac))
+		return PTR_ERR(st->gpio_ldac);


What's the intent of the above two gpio's? I would say, if we're not using them now, don't bother in adding them. Still ok to leave them in the bindings though.

they are actually on the eval board and if i dont drive them they are set as input. we need to make sure they are on the right state: CLR high and LDAC low (datasheet table9 p21) for the output to be set according to the register value when we write on spi xfer. I think we need to keep them.

nunojsa · 2024-10-16T11:28:33Z

drivers/iio/dac/ad5791.c

+	st->gpio_reset = devm_gpiod_get_optional(&spi->dev, "reset",
+						  GPIOD_OUT_LOW);
+	if (IS_ERR(st->gpio_reset))
+		return PTR_ERR(st->gpio_reset);


The above makes sense to have already. But do a reset in case we have it. Typical pattern is:

gpio_reset = devm_gpiod_get_optional(&spi->dev, "reset", GPIOD_OUT_HIGH); if (IS_ERR(gpio_reset)) return PTR_ERR(gpio_reset); if (gpio_reset) { // typically there's some time we need to wait for the reset to happen fseep(x); // get it out of reset gpiod_set_value_cansleep(gpio_reset, 0); }

drivers/iio/dac/ad5791.c

nunojsa · 2024-10-16T11:36:23Z

drivers/iio/dac/ad5791.c

-	st->pwr_down = pwr_down;
-
-	ret = ad5791_spi_write(st, AD5791_ADDR_CTRL, st->ctrl);
+	ret = __ad5791_dac_powerdown(indio_dev, pwr_down);


Unrelated change. Not disagreeing with it but should be in a separate patch. If you want to take it one step further, it even seems that some proper locking is missing... Moreover, we should set st->pwr_down after we actually do ad5791_spi_write(st, AD5791_ADDR_CTRL, st->ctrl)

i will drop this change and only check the power status in pre-enable. as you suggested below.

nunojsa · 2024-10-16T11:38:49Z

drivers/iio/dac/ad5791.c

+
+	if (spi_engine_ex_offload_supported(spi)) {
+		indio_dev->channels =
+			&ad5791_channels[spi_get_device_id(spi)->driver_data];


The above could also be an opportunity for a nice cleanup. Adding a chip_info structure and actual OF support. Thus getting rid of the id enum

nunojsa · 2024-10-16T11:42:19Z

drivers/iio/dac/ad5791.c

+	struct ad5791_state *st = iio_priv(indio_dev);
+	int ret;
+
+	ret = __ad5791_dac_powerdown(indio_dev, false);


I see now it's related but see below...

nunojsa · 2024-10-16T11:42:31Z

drivers/iio/dac/ad5791.c

+	pwm_disable(st->cnv_trigger);
+	spi_bus_unlock(st->spi->master);
+
+	return __ad5791_dac_powerdown(indio_dev, true);


Any reason to assume we want to powerdown the DAC? Since it's a user control I would rather check it and return error or something in ad5791_buffer_preenable() in case it's in a powerdown state. This would also mean that we can't power it down while in buffer mode. Thus, using iio_device_claim_direct_mode()

nunojsa · 2024-10-16T11:43:46Z

drivers/iio/dac/ad5791.c

+	int ret;
+
+	if (!st->cnv_trigger)
+		return -ENODEV;


AFAICT, this is only available for offload support and cnv_trigger is mandatory (otherwise we fail to probe). So, seems like a redundant check.

drivers/iio/dac/ad5791.c

dlech

A couple more suggestions for upstream "cleanup":

Use devm_regulator_get_enable_read_voltage() to simplify the regulator code.
Drop the driver remove callback by using more devm_.

Documentation/devicetree/bindings/iio/dac/adi,ad5791.yaml

arch/arm/boot/dts/socfpga_cyclone5_de10_nano.dtsi

arch/arm/boot/dts/socfpga_cyclone5_de10_nano_ad57xx.dts

Documentation/devicetree/bindings/iio/dac/adi,ad5791.yaml

drivers/iio/dac/ad5791.c

ahaslam2 · 2024-10-21T13:48:27Z

changes in V2:

implement new suggested driver simplifications:

Include chip_info in device match tables / remove chip id enum
use devm_regulator_get_enable_read_voltage on probe.

Fixes related to comments:

drop pwm DT binding
use devm_spi_optimize_message
dont power_up/down on enable
remove redundant trigger check
us hw pin reset if available
factor out offload setup from probe.
rebase after de10nano DT changes from uwe.

arch/arm/boot/dts/socfpga_cyclone5_de10_nano_ad57xx.dts

drivers/iio/dac/ad5791.c

dlech · 2024-10-21T21:08:15Z

drivers/iio/dac/ad5791.c

@@ -430,30 +412,9 @@ static int ad5791_probe(struct spi_device *spi)
 	indio_dev->name = st->chip_info->name;
 	ret = iio_device_register(indio_dev);
 	if (ret)
-		goto error_disable_reg_neg;
+		return dev_err_probe(&spi->dev, ret, "unable to register iio device\n");


Most drivers will just return devm_iio_device_register() directly, so don't usually have the dev_err_probe() here.

arch/arm/boot/dts/socfpga_cyclone5_de10_nano_hps.dtsi

ahaslam2 · 2024-10-22T13:48:07Z

changes in V3:

add patch to remove altr,gpio-bank-width in dt nodes
remove adi,channels node
fix macro style.
use fsleep
remove spi_set_drvdata
use devm_iio_device_register and delete remove callback.

drivers/iio/dac/ad5791.c

arch/arm/boot/dts/socfpga_cyclone5_de10_nano_ad57xx.dts

nunojsa · 2024-11-05T08:00:44Z

drivers/iio/dac/ad5791.c

+static int ad5791_get_sampling_freq(struct ad5791_state *st)
+{
+	return DIV_ROUND_CLOSEST_ULL(NSEC_PER_SEC,
+				     pwm_get_period(st->cnv_trigger));


Do we still want DIV_ROUND_CLOSEST_ULL()? @ukleinek seemed to have doubts about it...

i missed to address that. in fact is the same on the 400x driver. i guess we need to change both.

nunojsa · 2024-11-05T08:01:43Z

drivers/iio/dac/ad5791.c

+
+	st->spi_transfer.len = 4;
+	st->spi_transfer.bits_per_word = 24;
+	st->spi_transfer.tx_buf = (void *)-1; /* steaming tx */


nit: we could have a better comment for why we have to do this (ugly) hack

nunojsa · 2024-11-05T08:05:05Z

drivers/iio/dac/ad5791.c

+	if (st->pwr_down)
+		return -EINVAL;
+
+	ret =  pwm_enable(st->cnv_trigger);


Looks like we have an extra space?

yes. will remove.

nunojsa · 2024-11-05T08:18:13Z

drivers/iio/dac/ad5791.c

+	return devm_add_action_or_reset(&spi->dev, ad5791_pwm_disable,
+				       st->cnv_trigger);


I'm also wondering about the devm action. AFAICT, you're not enabling the PWM in __ad5791_set_sampling_freq() so this looks unbalanced... I guess this is not really a problem but also looks unnecessary.

ahaslam2 · 2024-11-05T09:41:42Z

Use 3 arguments for pwm node in dts

I don't see this change in arch/arm/boot/dts/socfpga_arria10_socdk_adrv9025.dts.

the device tree is actually: arch/arm/boot/dts/socfpga_cyclone5_de10_nano_ad57xx.dts
but i see what you mean, somehow this change did not get included in my push. will fix

nunojsa · 2024-11-05T09:55:11Z

drivers/iio/dac/ad5791.c

+	if (ret) {
+		ad5791_pwm_disable(st->cnv_trigger);
+		return ret;
+	}


Somehow this did not went in my review... Looks like a leftover

yes... i saw that! im remove the devm_action.

ahaslam2 · 2024-11-05T16:30:29Z

Changes V6:

remove devm_add_action_or_reset for pwm
use round_up for ad5791_get_sampling_freq
actually use pwm-cells <3>
add comment for tx_buf workaround for streaming tx.
fix space comments

dlech · 2024-11-05T16:37:57Z

arch/arm/boot/dts/socfpga_cyclone5_de10_nano_ad57xx.dts

+
+			dmas = <&tx_dma 0>;
+			dma-names = "tx";
+			pwms = <&adc_trigger 0 1000 0>;


Suggested change

pwms = <&adc_trigger 0 1000 0>;

pwms = <&dac_trigger 0 1000 0>;

Looks like a copy-paste from an ADC, but this is a DAC.

ahaslam2 · 2024-11-07T13:55:00Z

Changes v7

Follow ad7944 example, dont enable/disable pwm on buffer ops. just enable pwm on probe keep it enabled
this pwm is used for offload only. Bring back the devm_action to disable it automatically.
protect spi_read/write raw with "claim direct mode" and drop bus_lock from buffer ops.
use dac_trigger instead of adc in dts label.
add patch acked upsteam to correct dt example.

dlech · 2024-11-07T16:57:37Z

drivers/iio/dac/ad5791.c

+		return PTR_ERR(st->gpio_clear);
+
+	st->gpio_ldac = devm_gpiod_get_optional(&spi->dev, "ldac",
+						GPIOD_OUT_HIGH);


Does this also need to be changed to GPIOD_OUT_LOW since we changed the devcietree to active low?

might be for legacy reasons but i think the gpio wording is quite confusing
think that "HIGH" actually means "active" ? perhaps why we see several "resets" being
handled in opposite way when i think they are all "active low" ?

for the output to be set according to the DAC register value the actual state of the physical gpio needs to be low
(table 9 p 21 of datasheet) (reset=1 clr=1 ldac=0)

so by setting to out_high the gpio is actually going to low state if is "active low" in dts
at least that is what i measure and see on debugfs:

gpiochip0: GPIOs 2016-2047, parent: platform/ff210080.gpio_bd, /soc/axi_h2f_lw_bridge@0xff200000/gpio_bd@0x00010080:
gpio-2032 ( |reset ) out hi ACTIVE LOW
gpio-2033 ( |clear ) out hi ACTIVE LOW
gpio-2034 ( |ldac ) out lo ACTIVE LOW

think that "HIGH" actually means "active" ?

yes, or "asserted"

ahaslam2 · 2024-11-08T17:29:37Z

the ci error is due to the fixes tag from the upstream patch:
WARNING: Unknown commit id 'baaa92d284d5', maybe rebased or not pulled?
#10:
Fixes: baaa92d ("dt-bindings: iio: dac: ad5791: Add optional reset, clr and ldac gpios")

Depending on board layout, the ad57xx may need control of reset, clear, and ldac pins by the host driver. Add optional bindings for these gpios. Reviewed-by: David Lechner <[email protected]> Reviewed-by: Krzysztof Kozlowski <[email protected]> Signed-off-by: Axel Haslam <[email protected]> Link: https://patch.msgid.link/[email protected] Signed-off-by: Jonathan Cameron <[email protected]>

Vcc, iovcc, vrefp, and vrefn are needed for the DAC to work. Add them as required bindings for ad5791. Reviewed-by: David Lechner <[email protected]> Reviewed-by: Krzysztof Kozlowski <[email protected]> Signed-off-by: Axel Haslam <[email protected]> Link: https://patch.msgid.link/[email protected] Signed-off-by: Jonathan Cameron <[email protected]>

On the example, the ldac gpio is flagged as active high, when in reality its an active low gpio. Fix the example by using the active low flag for the ldac gpio. Signed-off-by: Axel Haslam <[email protected]>

Include a chip info struct in device SPI and device OF match tables to provide channel definitions for each particular ADC model and drop device enum. Suggested-by: Nuno Sa <[email protected]> Reviewed-by: David Lechner <[email protected]> Signed-off-by: Axel Haslam <[email protected]> Link: https://patch.msgid.link/[email protected] Signed-off-by: Jonathan Cameron <[email protected]>

The ad7591 has reset, clr and ldac gpios. For the DAC to output data continuously written to the data register the state of these gpios needs to be set by the driver. Add these gpios to the driver making them optional in case they are fixed on the pcb. Reviewed-by: David Lechner <[email protected]> Signed-off-by: Axel Haslam <[email protected]> Link: https://patch.msgid.link/[email protected] Signed-off-by: Jonathan Cameron <[email protected]>

Simplify probe by using of the devm_regulator_get_enable_read_voltage. Suggested-by: David Lechner <[email protected]> Reviewed-by: David Lechner <[email protected]> Signed-off-by: Axel Haslam <[email protected]> Link: https://patch.msgid.link/[email protected] Signed-off-by: Jonathan Cameron <[email protected]>

Use devm_iio_device_register to automatically free the iio device. since this is the last remaining resource that was not automatically freed, we can drop the ".remove" callback. Suggested-by: David Lechner <[email protected]> Reviewed-by: David Lechner <[email protected]> Signed-off-by: Axel Haslam <[email protected]> Link: https://patch.msgid.link/[email protected] Signed-off-by: Jonathan Cameron <[email protected]>

This property is not defined on the binidngs, and is not used by the driver. Remove it Suggested-by: David Lechner <[email protected]> Signed-off-by: Axel Haslam <[email protected]>

This adds the bi-directional gpio block to the d10 nano Signed-off-by: Axel Haslam <[email protected]>

Add devicetree for ad57xx on de10nano. Signed-off-by: Axel Haslam <[email protected]>

To allow offload to stream a "tx" type of xfer we need the write flag set but no messages on the SDO memory of the offload engine. but the current code relies on the tx_buf pointer for both of these operations, so there is no way to separate the two. The offload patches currently on development for upstream add flags on core spi structures to flag an offload xfer as a streaming xfer. While those patches get review and are ready to backport to the adi tree, Workaround this limitation by checking if the tx_buf address is -1 to flag it as "streaming type". Signed-off-by: Axel Haslam <[email protected]>

Add spi offload support to stream tx buffers using dma. This allows loading samples to the dac with a rate of 1 MSPS. Signed-off-by: Axel Haslam <[email protected]>

ahaslam2 · 2024-12-05T13:38:30Z

Changes re-based/tested on new kernel in main v6.6.

requires #2666

i remove the fixes tag, so CI would be happy.

ahaslam2 force-pushed the axelh/ad5791_offload branch 5 times, most recently from 802e9b1 to 3976d47 Compare October 15, 2024 15:55

ahaslam2 changed the title ~~Axelh/ad5791 offload~~ ad5791 offload Oct 15, 2024

ahaslam2 force-pushed the axelh/ad5791_offload branch 2 times, most recently from 03d271e to 65e5a18 Compare October 16, 2024 10:14

ahaslam2 marked this pull request as ready for review October 16, 2024 10:16

ahaslam2 requested review from nunojsa, mhennerich, dbogdan, btogorean, chegbeli, buha, amiclaus, rbolboac, danmois, CiprianRegus and machschmitt as code owners October 16, 2024 10:16

ahaslam2 requested a review from dlech October 16, 2024 10:17

nunojsa reviewed Oct 16, 2024

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ahaslam2 force-pushed the axelh/ad5791_offload branch from 65e5a18 to 5be52c8 Compare October 21, 2024 13:46

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ahaslam2 force-pushed the axelh/ad5791_offload branch 2 times, most recently from 0c0d193 to 9c53b59 Compare October 22, 2024 13:47

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ahaslam2 force-pushed the axelh/ad5791_offload branch 4 times, most recently from bb84d25 to 64fd6bb Compare November 5, 2024 16:27

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ahaslam2 force-pushed the axelh/ad5791_offload branch from 64fd6bb to 3f44a10 Compare November 7, 2024 13:52

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ahaslam2 added 12 commits December 5, 2024 10:37

dt-bindings: iio: dac: ad5791: ldac gpio is active low

fa8c040

On the example, the ldac gpio is flagged as active high, when in reality its an active low gpio. Fix the example by using the active low flag for the ldac gpio. Signed-off-by: Axel Haslam <[email protected]>

arm: dts: socfpga: Remove reference to gpio-bank-width

6e25006

This property is not defined on the binidngs, and is not used by the driver. Remove it Suggested-by: David Lechner <[email protected]> Signed-off-by: Axel Haslam <[email protected]>

arm: dts: de10_nano: Add bi-directional gpios

9728920

This adds the bi-directional gpio block to the d10 nano Signed-off-by: Axel Haslam <[email protected]>

arm: dts: de10_nano: Add support for ad57xx.

b6b259c

Add devicetree for ad57xx on de10nano. Signed-off-by: Axel Haslam <[email protected]>

iio: dac: ad5791: Add offload support

de61469

Add spi offload support to stream tx buffers using dma. This allows loading samples to the dac with a rate of 1 MSPS. Signed-off-by: Axel Haslam <[email protected]>

ahaslam2 force-pushed the axelh/ad5791_offload branch from 3f44a10 to de61469 Compare December 5, 2024 13:37

dlech mentioned this pull request Dec 9, 2024

Wip/bl/ad738x #2669

Merged

6 tasks

ahaslam2 merged commit a339b25 into main Dec 12, 2024
13 checks passed

ahaslam2 deleted the axelh/ad5791_offload branch December 12, 2024 09:58

		return devm_add_action_or_reset(&spi->dev, ad5791_pwm_disable,
		st->cnv_trigger);

	pwms = <&adc_trigger 0 1000 0>;
	pwms = <&dac_trigger 0 1000 0>;

ad5791 offload #2616

ad5791 offload #2616

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ahaslam2 commented Oct 15, 2024

spi offload support for ad57xx dac

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