linux-kernel - Re: [PATCH] drm: hdlcd: Update PM code to save/restore console.

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Message-ID: <926a4247-a62c-a64c-2349-52f63b1da2a0@tronnes.org>
Date:   Mon, 19 Jun 2017 17:45:21 +0200
From:   Noralf Trønnes <noralf@...nnes.org>
To:     Liviu Dudau <Liviu.Dudau@....com>
Cc:     Mali DP Maintainers <malidp@...s.arm.com>,
        DRI devel <dri-devel@...ts.freedesktop.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] drm: hdlcd: Update PM code to save/restore console.


Den 19.06.2017 15.17, skrev Liviu Dudau:
> On Fri, Jun 16, 2017 at 06:58:36PM +0200, Noralf Trønnes wrote:
>> Den 16.06.2017 15.53, skrev Liviu Dudau:
>>> Update the PM code to suspend/resume the fbdev_cma console.
>>>
>>> Signed-off-by: Liviu Dudau <Liviu.Dudau@....com>
>>> ---
>>>    drivers/gpu/drm/arm/hdlcd_drv.c | 11 ++++++++++-
>>>    1 file changed, 10 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/gpu/drm/arm/hdlcd_drv.c b/drivers/gpu/drm/arm/hdlcd_drv.c
>>> index d3da87fbd85a..89cd408cde6f 100644
>>> --- a/drivers/gpu/drm/arm/hdlcd_drv.c
>>> +++ b/drivers/gpu/drm/arm/hdlcd_drv.c
>>> @@ -13,6 +13,7 @@
>>>    #include <linux/spinlock.h>
>>>    #include <linux/clk.h>
>>>    #include <linux/component.h>
>>> +#include <linux/console.h>
>>>    #include <linux/list.h>
>>>    #include <linux/of_graph.h>
>>>    #include <linux/of_reserved_mem.h>
>>> @@ -435,9 +436,15 @@ static int __maybe_unused hdlcd_pm_suspend(struct device *dev)
>>>    		return 0;
>>>    	drm_kms_helper_poll_disable(drm);
>>> +	console_lock();
>>> +	drm_fbdev_cma_set_suspend(hdlcd->fbdev, 1);
>>> +	console_unlock();
>> You can use drm_fbdev_cma_set_suspend_unlocked() instead, it takes the
>> lock for you and can speed up resume if the lock is contented.
> Hi Noralf,
>
> Thanks for pointing out the helpful function. As you look to be the author of it,
> any reason why the signature of the function doesn't match the drm_fb_helper_ one
> being called through? (I'm talking about int vs bool for the state/suspend arguments).

I don't remember, but probably to match drm_fbdev_cma_set_suspend()
which uses int. drm_fb_helper_set_suspend*() uses bool, but calls
into fb_set_suspend() which uses int, but as a boolean.

Noralf.
> Best regards,
> Liviu
>
>> Noralf.
>>
>>
>>>    	hdlcd->state = drm_atomic_helper_suspend(drm);
>>>    	if (IS_ERR(hdlcd->state)) {
>>> +		console_lock();
>>> +		drm_fbdev_cma_set_suspend(hdlcd->fbdev, 0);
>>> +		console_unlock();
>>>    		drm_kms_helper_poll_enable(drm);
>>>    		return PTR_ERR(hdlcd->state);
>>>    	}
>>> @@ -454,8 +461,10 @@ static int __maybe_unused hdlcd_pm_resume(struct device *dev)
>>>    		return 0;
>>>    	drm_atomic_helper_resume(drm, hdlcd->state);
>>> +	console_lock();
>>> +	drm_fbdev_cma_set_suspend(hdlcd->fbdev, 0);
>>> +	console_unlock();
>>>    	drm_kms_helper_poll_enable(drm);
>>> -	pm_runtime_set_active(dev);
>>>    	return 0;
>>>    }