[Intel-gfx] [PATCH v2 1/2] drm/i915/mtl: Fix dram info readout

[Matt Roper]

On Thu, Nov 17, 2022 at 01:30:14PM -0800, Radhakrishna Sripada wrote:
> Register info read from the hardware is being cleared out. Preserve
> the register value and use extracted fields in the logic.

This description is kind of hard to understand if you don't already know
what the problem is (and the context in the diff itself doesn't show
enough of the function to make it clear either).  You might want to
clarify that we were overwriting the 'val' variable that code later in
the function still expects to contain the full register value.

With a reworded commit message,

Reviewed-by: Matt Roper <matthew.d.roper at intel.com>

> 
> Fixes: 825477e77912 ("drm/i915/mtl: Obtain SAGV values from MMIO instead of GT pcode mailbox")
> Cc: Matt Roper <matthew.d.roper at intel.com>
> Signed-off-by: Radhakrishna Sripada <radhakrishna.sripada at intel.com>
> ---
>  drivers/gpu/drm/i915/intel_dram.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_dram.c b/drivers/gpu/drm/i915/intel_dram.c
> index 2403ccd52c74..bba8cb6e8ae4 100644
> --- a/drivers/gpu/drm/i915/intel_dram.c
> +++ b/drivers/gpu/drm/i915/intel_dram.c
> @@ -471,8 +471,7 @@ static int xelpdp_get_dram_info(struct drm_i915_private *i915)
>  	u32 val = intel_uncore_read(&i915->uncore, MTL_MEM_SS_INFO_GLOBAL);
>  	struct dram_info *dram_info = &i915->dram_info;
>  
> -	val = REG_FIELD_GET(MTL_DDR_TYPE_MASK, val);
> -	switch (val) {
> +	switch (REG_FIELD_GET(MTL_DDR_TYPE_MASK, val)) {
>  	case 0:
>  		dram_info->type = INTEL_DRAM_DDR4;
>  		break;
> -- 
> 2.34.1
> 

-- 
Matt Roper
Graphics Software Engineer
VTT-OSGC Platform Enablement
Intel Corporation