Re: [Intel-xe] [PATCH v2 1/2] drm/xe: add skip_pcode flag

[Jani Nikula <jani.nikula@linux.intel.com>]

On Sun, 22 Oct 2023, Koby Elbaz <kelbaz@habana.ai> wrote:
> Per device, set this flag to enable access to the PCODE uC or to skip it.
>
> Signed-off-by: Koby Elbaz <kelbaz@habana.ai>
> ---
> Changes in v2:
> - Added the flag 'skip_pcode' instead of 'has_pcode'

I don't know why change was made from positive to negative flag.

Generally it's better to use positive flags, because they just read
better. Negative flags often lead to double negatives in source, such as
!disable.

Please consider using a positive flag, even if it's not "has_something".

BR,
Jani.


>
>  drivers/gpu/drm/xe/xe_device_types.h | 2 ++
>  drivers/gpu/drm/xe/xe_pci.c          | 2 ++
>  drivers/gpu/drm/xe/xe_pcode.c        | 9 +++++++++
>  3 files changed, 13 insertions(+)
>
> diff --git a/drivers/gpu/drm/xe/xe_device_types.h b/drivers/gpu/drm/xe/xe_device_types.h
> index 44d622d4cc3a..29199671d9e8 100644
> --- a/drivers/gpu/drm/xe/xe_device_types.h
> +++ b/drivers/gpu/drm/xe/xe_device_types.h
> @@ -257,6 +257,8 @@ struct xe_device {
>  		u8 enable_display:1;
>  		/** @bypass_mtcfg: Bypass Multi-Tile configuration from MTCFG register */
>  		u8 bypass_mtcfg:1;
> +		/** @skip_pcode: skip access to PCODE uC */
> +		u8 skip_pcode:1;
>  		/** @supports_mmio_ext: supports MMIO extension/s */
>  		u8 supports_mmio_ext:1;
>  		/** @has_heci_gscfi: device has heci gscfi */
> diff --git a/drivers/gpu/drm/xe/xe_pci.c b/drivers/gpu/drm/xe/xe_pci.c
> index 2fae45b9d88e..05b0aa9f2ab7 100644
> --- a/drivers/gpu/drm/xe/xe_pci.c
> +++ b/drivers/gpu/drm/xe/xe_pci.c
> @@ -61,6 +61,7 @@ struct xe_device_desc {
>  
>  	u8 has_llc:1;
>  	u8 bypass_mtcfg:1;
> +	u8 skip_pcode:1;
>  	u8 supports_mmio_ext:1;
>  };
>  
> @@ -578,6 +579,7 @@ static int xe_info_init(struct xe_device *xe,
>  	xe->info.media_name = media_desc ? media_desc->name : "none";
>  	xe->info.has_llc = desc->has_llc;
>  	xe->info.bypass_mtcfg = desc->bypass_mtcfg;
> +	xe->info.skip_pcode = desc->skip_pcode;
>  	xe->info.supports_mmio_ext = desc->supports_mmio_ext;
>  	xe->info.tile_mmio_ext_size = graphics_desc->tile_mmio_ext_size;
>  
> diff --git a/drivers/gpu/drm/xe/xe_pcode.c b/drivers/gpu/drm/xe/xe_pcode.c
> index 4a240acf7625..b324dc2a5deb 100644
> --- a/drivers/gpu/drm/xe/xe_pcode.c
> +++ b/drivers/gpu/drm/xe/xe_pcode.c
> @@ -61,6 +61,9 @@ static int pcode_mailbox_rw(struct xe_gt *gt, u32 mbox, u32 *data0, u32 *data1,
>  {
>  	int err;
>  
> +	if (gt_to_xe(gt)->info.skip_pcode)
> +		return 0;
> +
>  	lockdep_assert_held(&gt->pcode.lock);
>  
>  	if ((xe_mmio_read32(gt, PCODE_MAILBOX) & PCODE_READY) != 0)
> @@ -249,6 +252,9 @@ int xe_pcode_init(struct xe_gt *gt)
>  	int timeout_us = 180000000; /* 3 min */
>  	int ret;
>  
> +	if (gt_to_xe(gt)->info.skip_pcode)
> +		return 0;
> +
>  	if (!IS_DGFX(gt_to_xe(gt)))
>  		return 0;
>  
> @@ -280,6 +286,9 @@ int xe_pcode_probe(struct xe_gt *gt)
>  {
>  	drmm_mutex_init(&gt_to_xe(gt)->drm, &gt->pcode.lock);
>  
> +	if (gt_to_xe(gt)->info.skip_pcode)
> +		return 0;
> +
>  	if (!IS_DGFX(gt_to_xe(gt)))
>  		return 0;

-- 
Jani Nikula, Intel