[PATCH 13/13] drm/i915/xe3lpd: Use DMC wakelock by default

[Luca Coelho]

On Mon, 2024-10-21 at 19:27 -0300, Gustavo Sousa wrote:
> Although Bspec doesn't explicitly mentions that, as of Xe3_LPD, using
> DMC wakelock is the officially recommended way of accessing registers
> that would be off during DC5/DC6 and the legacy method (where the DMC
> intercepts MMIO to wake up the hardware) is to be avoided.
> 
> As such, update the driver to use the DMC wakelock by default starting
> with Xe3_LPD. Since the feature is somewhat new to the driver, also
> allow disabling it via a module parameter for debugging purposes.
> 
> For that, make the existing parameter allow values -1 (per-chip
> default), 0 (disabled) and 1 (enabled), similarly to what is done for
> other parameters.
> 
> Signed-off-by: Gustavo Sousa <gustavo.sousa at intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_display_params.c | 4 ++--
>  drivers/gpu/drm/i915/display/intel_display_params.h | 2 +-
>  drivers/gpu/drm/i915/display/intel_dmc_wl.c         | 6 +++++-
>  3 files changed, 8 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_display_params.c b/drivers/gpu/drm/i915/display/intel_display_params.c
> index 024de8abcb1a..bf00e5f1f145 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_params.c
> +++ b/drivers/gpu/drm/i915/display/intel_display_params.c
> @@ -123,10 +123,10 @@ intel_display_param_named_unsafe(enable_psr2_sel_fetch, bool, 0400,
>  	"(0=disabled, 1=enabled) "
>  	"Default: 1");
>  
> -intel_display_param_named_unsafe(enable_dmc_wl, bool, 0400,
> +intel_display_param_named_unsafe(enable_dmc_wl, int, 0400,
>  	"Enable DMC wakelock "
>  	"(0=disabled, 1=enabled) "
> -	"Default: 0");
> +	"Default: -1 (use per-chip default)");

We're already explaining the possible values in the previous
parentheses, so maybe the -1 should also be explained there?

--
Cheers,
Luca.