Re: [Intel-gfx] [PATCH v5 00/16] acpi/pwm/i915: Convert pwm-crc and i915 driver's PWM code to use the atomic PWM API

Re: [Intel-gfx] [PATCH v5 00/16] acpi/pwm/i915: Convert pwm-crc and i915 driver's PWM code to use the atomic PWM API

[Hans de Goede]

Hi Thierry,

On 7/30/20 11:26 AM, Thierry Reding wrote:
> On Wed, Jul 29, 2020 at 11:32:28AM +0200, Hans de Goede wrote:
>> cHi,
>>
>> On 7/29/20 10:23 AM, Andy Shevchenko wrote:
>>> On Mon, Jul 27, 2020 at 09:41:20AM +0200, Thierry Reding wrote:
>>>> On Fri, Jul 17, 2020 at 03:37:37PM +0200, Hans de Goede wrote:
>>>
>>>> I've applied patches 3 through 12 to the PWM tree. I thought it was a
>>>> bit odd that only a handful of these patches had been reviewed and there
>>>> were no Tested-bys, but I'm going to trust that you know what you're
>>>> doing. =) If this breaks things for anyone I'm sure they'll complain.
>>
>> Thank you for picking up these patches, but ...
>>
>>> Can we postpone a bit?
>>
>> I have to agree with Andy here, as mentioned my plan was to push the
>> entire series through drm-intel-next-queued once the last few PWM
>> patches are reviewed.
>>
>> There are some fixes, to the pwm-crc driver which change behavior in
>> a possibly undesirable way, unless combined with the i915 changes.
>>
>> E.g. there is a fix which makes the pwm-crc driver actually honor
>> the requested output frequency (it was not doing this due to a bug)
>> and before the i915 changes, the i915 driver was hardcoding an output
>> freq, rather then looking at the video-bios-tables as it should.
>>
>> So having just the pwm-crc fix, will change the output frequency
>> which some LCD panels might not like.
>>
>> Note things are probably fine with the hardcoded output freq, but I
>> would like to play it safe here.
>>
>> Also Andy was still reviewing some of the PWM patches, and has requested
>> changes to 1 patch, nothing functional just some code-reshuffling for
>> cleaner code, so we could alternatively fix this up with a follow-up patch.
>>
>> Either way please let us know how you want to proceed.
> 
> Okay, that's fine, I'll drop them again.

Great, thank you.

>>>> That said I see that Rafael has acked patches 1-2 and Jani did so for
>>>> patches 13-16. I'm not sure if you expect me to pick those patches up as
>>>> well. As far as I can tell the ACPI, PWM and DRM parts are all
>>>> independent, so these patches could be applied to the corresponding
>>>> subsystem trees.
>>>>
>>>> Anyway, if you want me to pick those all up into the PWM tree, I suppose
>>>> that's something I can do as well.
>>
>> drm-intel-next-queued is usually seeing quite a bit of churn, so the i915
>> patches really should go upstream through that branch.
> 
> During my build tests I ran into a small issue caused by this series
> interacting with the conversion of period and duty-cycle to u64 that
> I've queued for v5.9. This causes a build failure on x86.
> 
> I have this local diff to fix that:
> 
> --- >8 ---
> diff --git a/drivers/pwm/pwm-crc.c b/drivers/pwm/pwm-crc.c
> index 370ab826a20b..92e838797733 100644
> --- a/drivers/pwm/pwm-crc.c
> +++ b/drivers/pwm/pwm-crc.c
> @@ -76,7 +76,9 @@ static int crc_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
>   
>   	if (pwm_get_duty_cycle(pwm) != state->duty_cycle ||
>   	    pwm_get_period(pwm) != state->period) {
> -		int level = state->duty_cycle * PWM_MAX_LEVEL / state->period;
> +		u64 level = state->duty_cycle * PWM_MAX_LEVEL;
> +
> +		do_div(level, state->period);
>   
>   		err = regmap_write(crc_pwm->regmap, PWM0_DUTY_CYCLE, level);
>   		if (err) {
> @@ -141,10 +143,9 @@ static void crc_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
>   
>   	clk_div = (clk_div_reg & ~PWM_OUTPUT_ENABLE) + 1;
>   
> -	state->period =
> -		DIV_ROUND_UP(clk_div * NSEC_PER_USEC * 256, PWM_BASE_CLK_MHZ);
> -	state->duty_cycle =
> -		DIV_ROUND_UP(duty_cycle_reg * state->period, PWM_MAX_LEVEL);
> +	state->period = DIV_ROUND_UP(clk_div * NSEC_PER_USEC * 256, PWM_BASE_CLK_MHZ);
> +	state->duty_cycle = duty_cycle_reg * state->period + PWM_MAX_LEVEL - 1;
> +	do_div(state->duty_cycle, PWM_MAX_LEVEL);
>   	state->polarity = PWM_POLARITY_NORMAL;
>   	state->enabled = !!(clk_div_reg & PWM_OUTPUT_ENABLE);
>   }
> --- >8 ---
> 
> So perhaps you want to integrate that or something equivalent into your
> series.

Ack, thank you for letting me know.

> Also this could result in a tricky dependency between PWM and drm-misc,
> although if you're targetting drm-misc it's too late for v5.9 anyway. In
> that case you should be able to rebase your series on v5.9-rc1 when it's
> out and then you'll get the prerequisite PWM changes for the u64
> conversion as part of that. No need to track the dependency explicitly.

Right, I agree that this is too late for this cycle, so I will rebase it
on top of v5.9-rc1 once that is out, making sure to take the u64 changes
into account.

As said my plan is to merge this all through the drm tree, the assumption
there was that the pwm-crc and pwm-lpss drivers normally do not see a whole
lot of chsnges. Rebasing on top of 5.9-rc1 should take care of the u64
changes. So unless there are more pwm-core changes planned for the 5.10
cycle, I would like to queue this in the drm-intel tree for 5.10.
By thta time Andy and I should have also wrapped up the review process
(it is as good as wrapped up now already).

Thierry, is merging these through the drm-intel tree for 5.10 ok with
you? And if this is ok with you may I add your Acked-by to the PWM
patches to indicate this ?

Regards,

Hans


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Re: [Intel-gfx] [PATCH v5 00/16] acpi/pwm/i915: Convert pwm-crc and i915 driver's PWM code to use the atomic PWM API

[Hans de Goede]

Hi,

On 7/29/20 12:54 PM, Andy Shevchenko wrote:
> On Fri, Jul 17, 2020 at 03:37:37PM +0200, Hans de Goede wrote:
>> Hi All,
>>
>> Here is v5 of my patch series converting the i915 driver's code for
>> controlling the panel's backlight with an external PWM controller to
>> use the atomic PWM API. See below for the changelog.
>>
>> This series consists of 4 parts:
>>
>> 1. acpi_lpss fixes workarounds for Cherry Trail DSTD nastiness
>> 2. various fixes to the pwm-lpss driver
>> 3. convert the pwm-crc driver to support the atomic PWM API and
>> 4. convert the i915 driver's PWM code to use the atomic PWM API
>>
>> The involved acpi_lpss and pwm drivers do not see a whole lot of churn,
>> so the plan is to merge this all through drm-intel-next-queued (dinq)
>> once all the patches are reviewed / have acks.
>>
>> Specifically patches 5-9, 11 still need an Acked- / Reviewed-by
>>
>> Andy, can you please take a look at the unreviewed patches? Specifically
>> patches 5-6 should address your review remarks from v4 of this set
>> and I've addressed your review remarks on patches 7-9 in v3 already.
>> A review of patch 11 would also be welcome
> 
> Done. Sorry for a delay.
> 
> One comment to consider, though. There are three channels in that PWM AFAIU.
> One of them is backlight control, another one can be attached to haptics. The
> concern is how this series may (or may not?) affect haptics behaviour.

When you say "in that PWM" do you mean the LPSS one or the CRC one ?

The LPSS patches are all fixes, they don't change behavior, so those
should be fine for the haptics.

The CRC PWM driver patches do make it honor the requested output frequency,
where before, because of a bug, it would stick with the out frequency
setup by the firmware (or the power-on-reset value if no value is set
by the firmware). This fix causing this is very clearly correct, but
it could have unexpected side-effects.

However I guess that you are talking about the LPSS PWM controllers
and there I expect no impact on haptic or other non backlight users
from these changes.

Regards,

Hans

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Re: [Intel-gfx] [PATCH v5 00/16] acpi/pwm/i915: Convert pwm-crc and i915 driver's PWM code to use the atomic PWM API

[Andy Shevchenko]

On Sat, Aug 01, 2020 at 04:38:16PM +0200, Hans de Goede wrote:
> On 7/29/20 12:54 PM, Andy Shevchenko wrote:
> > On Fri, Jul 17, 2020 at 03:37:37PM +0200, Hans de Goede wrote:

...

> > One comment to consider, though. There are three channels in that PWM AFAIU.
> > One of them is backlight control, another one can be attached to haptics. The
> > concern is how this series may (or may not?) affect haptics behaviour.
> 
> When you say "in that PWM" do you mean the LPSS one or the CRC one ?

CRC one. I have read it from PMIC spec, that's why the question.

> The CRC PWM driver patches do make it honor the requested output frequency,
> where before, because of a bug, it would stick with the out frequency
> setup by the firmware (or the power-on-reset value if no value is set
> by the firmware). This fix causing this is very clearly correct, but
> it could have unexpected side-effects.

-- 
With Best Regards,
Andy Shevchenko


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Re: [Intel-gfx] [PATCH v5 00/16] acpi/pwm/i915: Convert pwm-crc and i915 driver's PWM code to use the atomic PWM API

[Hans de Goede]

Hi,

On 8/2/20 1:25 PM, Andy Shevchenko wrote:
> On Sat, Aug 01, 2020 at 04:38:16PM +0200, Hans de Goede wrote:
>> On 7/29/20 12:54 PM, Andy Shevchenko wrote:
>>> On Fri, Jul 17, 2020 at 03:37:37PM +0200, Hans de Goede wrote:
> 
> ...
> 
>>> One comment to consider, though. There are three channels in that PWM AFAIU.
>>> One of them is backlight control, another one can be attached to haptics. The
>>> concern is how this series may (or may not?) affect haptics behaviour.
>>
>> When you say "in that PWM" do you mean the LPSS one or the CRC one ?
> 
> CRC one. I have read it from PMIC spec, that's why the question.

Ah I see, well the kernel driver only implements support for 1 PWM output,
the one which is used for the backlight brighness control.

So this series should not affect haptics behavior, since it looks like
the haptic functionality is not supported in the mainline kernel at all.

And I'm also not aware of any tablets with a CRC PMIC which have
(non working) haptic support.

Regards,

Hans

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Re: [Intel-gfx] [PATCH v5 06/16] pwm: lpss: Use pwm_lpss_apply() when restoring state on resume

[Hans de Goede]

Hi,

On 7/29/20 10:12 AM, Andy Shevchenko wrote:
> On Tue, Jul 28, 2020 at 09:55:22PM +0200, Hans de Goede wrote:
>> On 7/28/20 8:57 PM, Andy Shevchenko wrote:
>>> On Fri, Jul 17, 2020 at 03:37:43PM +0200, Hans de Goede wrote:
> 
> ...
> 
>>> Maybe I'm too picky, but I would go even further and split apply to two versions
>>>
>>> static int pwm_lpss_apply_on_resume(struct pwm_chip *chip, struct pwm_device *pwm,
>>> 			  const struct pwm_state *state)
>>>>    {
>>>>    	struct pwm_lpss_chip *lpwm = to_lpwm(chip);
>>>>    	if (state->enabled)
>>>>    		return pwm_lpss_prepare_enable(lpwm, pwm, state, !pwm_is_enabled(pwm));
>>>>    	if (pwm_is_enabled(pwm)) {
>>>>    		pwm_lpss_write(pwm, pwm_lpss_read(pwm) & ~PWM_ENABLE);
>>>>    	return 0;
>>>>    }
>>>
>>> and another one for !from_resume.
>>
>> It is a bit picky :) But that is actually not a bad idea, although I would write
>> it like this for more symmetry with the normal (not on_resume) apply version,
>> while at it I also renamed the function:
>>
>> /*
>>   * This is a mirror of pwm_lpss_apply() without pm_runtime reference handling
>>   * for restoring the PWM state on resume.
>>   */
>> static int pwm_lpss_restore_state(struct pwm_chip *chip, struct pwm_device *pwm,
>>                                    const struct pwm_state *state)
>> {
>>     	struct pwm_lpss_chip *lpwm = to_lpwm(chip);
>> 	int ret = 0;
>>
>>     	if (state->enabled)
>>     		ret = pwm_lpss_prepare_enable(lpwm, pwm, state, !pwm_is_enabled(pwm));
>>     	else if (pwm_is_enabled(pwm))
>>     		pwm_lpss_write(pwm, pwm_lpss_read(pwm) & ~PWM_ENABLE);
>>
>>     	return ret;
>> }
>>
>> Would that work for you?
> 
> Yes.

Ok, I've added the suggested/discussed helper in my personal tree. Is it ok
if I add your Reviewed-by with that change in place. This is the last unreviewed
bit, so I would rather not respin the series just for this (there will be one
more respin when I rebase it on 5.9-rc1).

If you want to check out what the patch looks like now, the new version from
my personal tree is here:

https://github.com/jwrdegoede/linux-sunxi/commit/e4869830d88bb8cb8251718e0086ac189abc0f56

Regards,

Hans

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Re: [Intel-gfx] [PATCH v5 06/16] pwm: lpss: Use pwm_lpss_apply() when restoring state on resume

[Andy Shevchenko]

On Sun, Aug 02, 2020 at 10:51:34PM +0200, Hans de Goede wrote:
> On 7/29/20 10:12 AM, Andy Shevchenko wrote:

...

> Ok, I've added the suggested/discussed helper in my personal tree. Is it ok
> if I add your Reviewed-by with that change in place.

Yes, go ahead!

> This is the last unreviewed
> bit, so I would rather not respin the series just for this (there will be one
> more respin when I rebase it on 5.9-rc1).
> 
> If you want to check out what the patch looks like now, the new version from
> my personal tree is here:
> 
> https://github.com/jwrdegoede/linux-sunxi/commit/e4869830d88bb8cb8251718e0086ac189abc0f56

Thanks, looks good to me.

-- 
With Best Regards,
Andy Shevchenko


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