Re: [PATCH v4] drm/amdgpu: Disable ABM when AC mode

[Harry Wentland <harry.wentland@amd.com>]

On 2022-04-27 04:08, Ryan Lin wrote:
> Disable ABM feature when the system is running on AC mode to get the more
> perfect contrast of the display.
> 
> v2: remove "UPSTREAM" from the subject.
> 
> v3: adv->pm.ac_power updating by amd gpu_acpi_event_handler.
> 
> V4: Add the file I lost to fix the build error.
> 
> Signed-off-by: Ryan Lin <tsung-hua.lin@amd.com>
> 
> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c      |  3 +-
>   drivers/gpu/drm/amd/amdgpu/amdgpu_device.c    |  1 +
>   drivers/gpu/drm/amd/display/dc/dce/dmub_abm.c | 61 +++++++++++--------
>   drivers/gpu/drm/amd/include/amd_acpi.h        |  1 +
>   drivers/gpu/drm/amd/pm/inc/amdgpu_dpm.h       |  1 +
>   5 files changed, 42 insertions(+), 25 deletions(-)
> 
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c
> index 4811b0faafd9a..6ac331ee4255d 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c
> @@ -822,7 +822,8 @@ 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, ACPI_AC_CLASS) == 0) {
> +	if (strcmp(entry->device_class, ACPI_AC_CLASS) == 0 ||
> +	    strcmp(entry->device_class, ACPI_BATTERY_CLASS) == 0) {
>   		if (power_supply_is_system_supplied() > 0)
>   			DRM_DEBUG_DRIVER("pm: AC\n");
>   		else
> 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..090bd23410b45 100644
> --- a/drivers/gpu/drm/amd/display/dc/dce/dmub_abm.c
> +++ b/drivers/gpu/drm/amd/display/dc/dce/dmub_abm.c
> @@ -22,7 +22,8 @@
>    * Authors: AMD
>    *
>    */
> -
> +#include <linux/power_supply.h>
> +#include "amdgpu.h"
>   #include "dmub_abm.h"
>   #include "dce_abm.h"
>   #include "dc.h"
> @@ -50,7 +51,7 @@
>   
>   #define DISABLE_ABM_IMMEDIATELY 255
>   
> -
> +extern uint amdgpu_dm_abm_level;
>   
>   static void dmub_abm_enable_fractional_pwm(struct dc_context *dc)
>   {
> @@ -117,28 +118,6 @@ 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;
> @@ -147,6 +126,10 @@ static bool dmub_abm_set_level(struct abm *abm, uint32_t level)
>   	int i;
>   	int edp_num;
>   	uint8_t panel_mask = 0;
> +	struct amdgpu_device *dev = dc->driver_context;

NAK. We can't access amdgpu_device in DC. This is code that's
shared with other OSes.

I've mentioned this in my previous review a month ago.

What happened to the other suggestion I had? I never saw
a follow-up.

My previous comments, copy-pasted here again. Please address
or answer why you disagree:

>>
>> This patch still has the problem of accessing adev from within DC.
>> That'll break things on other platforms. This information needs to
>> come in through the DC interface if we want to enable/disable ABM in
>> this function.
>>
>> After a closer look I also don't think that amdgpu is the right place
>> to control the logic to disable ABM in AC mode, i.e. to switch between
>> ABM levels. Take a look at dm_connector_state.abm_level and the
>> abm_level_property. It's exposed to userspace as "abm level".
>>
>> The "abm level" defaults to "0" unless userspace sets the "abm level"
>> to something else. The same component that sets the "abm level"
>> initially is the one that should set it to "0" when in AC mode.
>>
> 
> It might be that the ABM level is controlled via the abmlevel module
> parameter. If that's the case and there isn't a userspace that sets the
> "abm level" property then the easiest way to handle this is to switch
> between 0 and amdgpu_dm_abm_level inside amdgpu_dm when there is a
> AC/DC switch. Either way we shouldn't need to change DC.

Thanks,
Harry

> +
> +	if (dev->pm.ac_power)
> +		level = 0;
>   
>   	get_edp_links(dc->dc, edp_links, &edp_num);
>   
> @@ -170,6 +153,36 @@ 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/include/amd_acpi.h b/drivers/gpu/drm/amd/include/amd_acpi.h
> index 2d089d30518f3..5a62e580668e4 100644
> --- a/drivers/gpu/drm/amd/include/amd_acpi.h
> +++ b/drivers/gpu/drm/amd/include/amd_acpi.h
> @@ -25,6 +25,7 @@
>   #define AMD_ACPI_H
>   
>   #define ACPI_AC_CLASS           "ac_adapter"
> +#define ACPI_BATTERY_CLASS  "battery"
>   
>   struct atif_verify_interface {
>   	u16 size;		/* structure size in bytes (includes size field) */
> 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;
>