Re: [PATCH v1 1/4] drm/xe/pcode: Introduce xe_pcode_read_probe()

[Michal Wajdeczko <michal.wajdeczko@intel.com>]

On 11/18/2025 9:59 AM, Raag Jadav wrote:
> If the device is running older pcode firmware, it is possible that newer
> mailbox commands are not supported by it. The respective functionality
> isn't useful in that case but nor is error logging, as it doesn't
> particularly signify anything wrong with pcode firmware or device as a
> whole. Introduce xe_pcode_read_probe() which allows the caller to check
> for mailbox command support and determine if the respective functionality
> exists on the device without it being reported as an error. This is useful
> in cases where we want to make functionality decisions in the driver based
> on pcode return codes and a relatively simpler design choice compared to
> other solutions like checking pcode firmware version, which comes with
> additional complexity of binding every single command to a specific version
> and deems pcode commands useless in case the driver fails to obtain it for
> reasons unrelated to pcode.

s/pcode/PCODE

as in the message below you are using "PCODE", so IMO the same naming should everywhere, including commit message

> 
> This only silences command related failures and still reports other
> failures as errors, so we don't end up hiding the genuine ones.
> 
> Suggested-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Signed-off-by: Raag Jadav <raag.jadav@intel.com>
> ---
>  drivers/gpu/drm/xe/xe_pcode.c | 42 ++++++++++++++++++++++++-----------
>  drivers/gpu/drm/xe/xe_pcode.h |  1 +
>  2 files changed, 30 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_pcode.c b/drivers/gpu/drm/xe/xe_pcode.c
> index 0d33c14ea0cf..797b757f7a68 100644
> --- a/drivers/gpu/drm/xe/xe_pcode.c
> +++ b/drivers/gpu/drm/xe/xe_pcode.c
> @@ -30,7 +30,7 @@
>   * - PCODE for display operations
>   */
>  
> -static int pcode_mailbox_status(struct xe_tile *tile)
> +static int pcode_mailbox_status(struct xe_tile *tile, bool probe)
>  {
>  	const char *err_str;
>  	int err_decode;
> @@ -57,8 +57,12 @@ static int pcode_mailbox_status(struct xe_tile *tile)
>  	}
>  
>  	if (err) {
> -		drm_err(&tile_to_xe(tile)->drm, "PCODE Mailbox failed: %d %s",
> -			err_decode, err_str);
> +		if (probe && err_decode == -ENXIO)
> +			drm_dbg(&tile_to_xe(tile)->drm, "PCODE Mailbox unsupported: %d %s",
> +				err_decode, err_str);
> +		else
> +			drm_err(&tile_to_xe(tile)->drm, "PCODE Mailbox failed: %d %s",
> +				err_decode, err_str);

for tile-related messages, we have dedicated tile-specific helpers:

#include "xe_tile_printk.h"

	xe_tile_err(tile, ....)
	xe_tile_dbg(tile, ....)