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

["Christian König" <christian.koenig@amd.com>]

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.

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;
>>