Re: [PATCH v2 3/25] drm/amdgpu: Disable ABM when AC mode

[Daniel Vetter <daniel@ffwll.ch>]

On Fri, Mar 25, 2022 at 08:22:29AM +0100, Christian König wrote:
> Hi Ryan,
> 
> we should try to avoid that and if it isn't possible at least use some
> constant like ACPI_AC_CLASS.
> 
> Could be that the information isn't available otherwise. Alex should know
> more about that.

I wonder whether we shouldn't need a more dedicated notification from acpi
for power supply events instead of stitching this together ourselves. At
least this kind of stuff feels more into the policy/tuning territory where
a bit more careful interfaces might be good instead of just "hey there's
this very funny acpi protocol we just have to take part in to not upset
the hw/fw".
-Daniel

> 
> Regards,
> Christian.
> 
> Am 25.03.22 um 08:09 schrieb Lin, Tsung-hua (Ryan):
> > [AMD Official Use Only]
> > 
> > Hi Christian,
> > 
> > There is already a string comparison in the same function. I just reference that to port this solution.
> > 
> > 
> > 
> > #define ACPI_AC_CLASS           "ac_adapter"
> > 
> > 
> > static int amdgpu_acpi_event(struct notifier_block *nb,
> > 			     unsigned long val,
> > 			     void *data)
> > {
> > 	struct amdgpu_device *adev = container_of(nb, struct amdgpu_device, acpi_nb);
> > 	struct acpi_bus_event *entry = (struct acpi_bus_event *)data;
> > 
> > +	if (strcmp(entry->device_class, "battery") == 0) {
> > +		adev->pm.ac_power = power_supply_is_system_supplied() > 0;
> > +	}
> > 
> > 	if (strcmp(entry->device_class, ACPI_AC_CLASS) == 0) {      <-------------------here!
> > 		if (power_supply_is_system_supplied() > 0)
> > 			DRM_DEBUG_DRIVER("pm: AC\n");
> > 		else
> > 			DRM_DEBUG_DRIVER("pm: DC\n");
> > 
> > 		amdgpu_pm_acpi_event_handler(adev);
> > 	}
> > 
> > 	/* Check for pending SBIOS requests */
> > 	return amdgpu_atif_handler(adev, entry);
> > }
> > 
> > Thanks,
> > Ryan Lin.
> > 
> > -----Original Message-----
> > From: Koenig, Christian <Christian.Koenig@amd.com>
> > Sent: Friday, March 25, 2022 2:58 PM
> > To: Lin, Tsung-hua (Ryan) <Tsung-hua.Lin@amd.com>; Wentland, Harry <Harry.Wentland@amd.com>; Li, Sun peng (Leo) <Sunpeng.Li@amd.com>; Deucher, Alexander <Alexander.Deucher@amd.com>; David1.Zhou@amd.com; airlied@linux.ie; daniel@ffwll.ch; seanpaul@chromium.org; bas@basnieuwenhuizen.nl; Kazlauskas, Nicholas <Nicholas.Kazlauskas@amd.com>; sashal@kernel.org; markyacoub@google.com; victorchengchi.lu@amd.com; ching-shih.li@amd.corp-partner.google.com; Siqueira, Rodrigo <Rodrigo.Siqueira@amd.com>; ddavenport@chromium.org; amd-gfx@lists.freedesktop.org; dri-devel@lists.freedesktop.org; linux-kernel@vger.kernel.org; Li, Leon <Leon.Li@amd.com>
> > Subject: Re: [PATCH v2 3/25] drm/amdgpu: Disable ABM when AC mode
> > 
> > Am 25.03.22 um 05:05 schrieb Ryan Lin:
> > > Disable ABM feature when the system is running on AC mode to get the
> > > more perfect contrast of the display.
> > > 
> > > Signed-off-by: Ryan Lin <tsung-hua.lin@amd.com>
> > > 
> > > ---
> > >    drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c      |  4 ++
> > >    drivers/gpu/drm/amd/amdgpu/amdgpu_device.c    |  1 +
> > >    drivers/gpu/drm/amd/display/dc/dce/dmub_abm.c | 58 ++++++++++++-------
> > >    drivers/gpu/drm/amd/pm/inc/amdgpu_dpm.h       |  1 +
> > >    4 files changed, 42 insertions(+), 22 deletions(-)
> > > 
> > > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c
> > > b/drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c
> > > index c560c1ab62ecb..bc8bb9aad2e36 100644
> > > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c
> > > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c
> > > @@ -822,6 +822,10 @@ static int amdgpu_acpi_event(struct notifier_block *nb,
> > >    	struct amdgpu_device *adev = container_of(nb, struct amdgpu_device, acpi_nb);
> > >    	struct acpi_bus_event *entry = (struct acpi_bus_event *)data;
> > > +	if (strcmp(entry->device_class, "battery") == 0) {
> > String comparison in a hot path is not something we usually like to see in the kernel.
> > 
> > Isn't there any other way to detect that? Like a flag or similar?
> > 
> > Regards,
> > Christian.
> > 
> > > +		adev->pm.ac_power = power_supply_is_system_supplied() > 0;
> > > +	}
> > > +
> > >    	if (strcmp(entry->device_class, ACPI_AC_CLASS) == 0) {
> > >    		if (power_supply_is_system_supplied() > 0)
> > >    			DRM_DEBUG_DRIVER("pm: AC\n");
> > > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> > > b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> > > index abfcc1304ba0c..3a0afe7602727 100644
> > > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> > > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> > > @@ -3454,6 +3454,7 @@ int amdgpu_device_init(struct amdgpu_device
> > > *adev,
> > >    	adev->gfx.gfx_off_req_count = 1;
> > >    	adev->pm.ac_power = power_supply_is_system_supplied() > 0;
> > > +	adev->pm.old_ac_power = true;
> > >    	atomic_set(&adev->throttling_logging_enabled, 1);
> > >    	/*
> > > diff --git a/drivers/gpu/drm/amd/display/dc/dce/dmub_abm.c
> > > b/drivers/gpu/drm/amd/display/dc/dce/dmub_abm.c
> > > index 54a1408c8015c..478a734b66926 100644
> > > --- a/drivers/gpu/drm/amd/display/dc/dce/dmub_abm.c
> > > +++ b/drivers/gpu/drm/amd/display/dc/dce/dmub_abm.c
> > > @@ -23,6 +23,8 @@
> > >     *
> > >     */
> > > +#include <linux/power_supply.h>
> > > +#include "amdgpu.h"
> > >    #include "dmub_abm.h"
> > >    #include "dce_abm.h"
> > >    #include "dc.h"
> > > @@ -51,6 +53,7 @@
> > >    #define DISABLE_ABM_IMMEDIATELY 255
> > > +extern uint amdgpu_dm_abm_level;
> > >    static void dmub_abm_enable_fractional_pwm(struct dc_context *dc)
> > >    {
> > > @@ -117,28 +120,6 @@ static void dmub_abm_init(struct abm *abm, uint32_t backlight)
> > >    	dmub_abm_enable_fractional_pwm(abm->ctx);
> > >    }
> > > -static unsigned int dmub_abm_get_current_backlight(struct abm *abm)
> > > -{
> > > -	struct dce_abm *dce_abm = TO_DMUB_ABM(abm);
> > > -	unsigned int backlight = REG_READ(BL1_PWM_CURRENT_ABM_LEVEL);
> > > -
> > > -	/* return backlight in hardware format which is unsigned 17 bits, with
> > > -	 * 1 bit integer and 16 bit fractional
> > > -	 */
> > > -	return backlight;
> > > -}
> > > -
> > > -static unsigned int dmub_abm_get_target_backlight(struct abm *abm) -{
> > > -	struct dce_abm *dce_abm = TO_DMUB_ABM(abm);
> > > -	unsigned int backlight = REG_READ(BL1_PWM_TARGET_ABM_LEVEL);
> > > -
> > > -	/* return backlight in hardware format which is unsigned 17 bits, with
> > > -	 * 1 bit integer and 16 bit fractional
> > > -	 */
> > > -	return backlight;
> > > -}
> > > -
> > >    static bool dmub_abm_set_level(struct abm *abm, uint32_t level)
> > >    {
> > >    	union dmub_rb_cmd cmd;
> > > @@ -148,6 +129,9 @@ static bool dmub_abm_set_level(struct abm *abm, uint32_t level)
> > >    	int edp_num;
> > >    	uint8_t panel_mask = 0;
> > > +	if (power_supply_is_system_supplied() > 0)
> > > +		level = 0;
> > > +
> > >    	get_edp_links(dc->dc, edp_links, &edp_num);
> > >    	for (i = 0; i < edp_num; i++) {
> > > @@ -170,6 +154,36 @@ static bool dmub_abm_set_level(struct abm *abm, uint32_t level)
> > >    	return true;
> > >    }
> > > +static unsigned int dmub_abm_get_current_backlight(struct abm *abm) {
> > > +	struct dce_abm *dce_abm = TO_DMUB_ABM(abm);
> > > +	unsigned int backlight = REG_READ(BL1_PWM_CURRENT_ABM_LEVEL);
> > > +	struct dc_context *dc = abm->ctx;
> > > +	struct amdgpu_device *adev = dc->driver_context;
> > > +
> > > +	if (adev->pm.ac_power != adev->pm.old_ac_power) {
> > > +		dmub_abm_set_level(abm, amdgpu_dm_abm_level);
> > > +		adev->pm.ac_power = power_supply_is_system_supplied() > 0;
> > > +		adev->pm.old_ac_power = adev->pm.ac_power;
> > > +	}
> > > +
> > > +	/* return backlight in hardware format which is unsigned 17 bits, with
> > > +	 * 1 bit integer and 16 bit fractional
> > > +	 */
> > > +	return backlight;
> > > +}
> > > +
> > > +static unsigned int dmub_abm_get_target_backlight(struct abm *abm) {
> > > +	struct dce_abm *dce_abm = TO_DMUB_ABM(abm);
> > > +	unsigned int backlight = REG_READ(BL1_PWM_TARGET_ABM_LEVEL);
> > > +
> > > +	/* return backlight in hardware format which is unsigned 17 bits, with
> > > +	 * 1 bit integer and 16 bit fractional
> > > +	 */
> > > +	return backlight;
> > > +}
> > > +
> > >    static bool dmub_abm_init_config(struct abm *abm,
> > >    	const char *src,
> > >    	unsigned int bytes,
> > > diff --git a/drivers/gpu/drm/amd/pm/inc/amdgpu_dpm.h
> > > b/drivers/gpu/drm/amd/pm/inc/amdgpu_dpm.h
> > > index f6e0e7d8a0077..de459411a0e83 100644
> > > --- a/drivers/gpu/drm/amd/pm/inc/amdgpu_dpm.h
> > > +++ b/drivers/gpu/drm/amd/pm/inc/amdgpu_dpm.h
> > > @@ -445,6 +445,7 @@ struct amdgpu_pm {
> > >    	uint32_t                smu_prv_buffer_size;
> > >    	struct amdgpu_bo        *smu_prv_buffer;
> > >    	bool ac_power;
> > > +	bool old_ac_power;
> > >    	/* powerplay feature */
> > >    	uint32_t pp_feature;
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch