Re: [PATCH v3] drm/i915/display: Mask RO bits in gen9_write_dc_state()

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

On Wed, 03 Jun 2026, Imre Deak <imre.deak@intel.com> wrote:
> On Wed, Jun 03, 2026 at 11:30:04AM +0300, Jani Nikula wrote:
>> On Tue, 02 Jun 2026, Dibin Moolakadan Subrahmanian <dibin.moolakadan.subrahmanian@intel.com> wrote:
>> > +static u32 dc_state_ro_mask(struct intel_display *display)
>> > +{
>> > +	if (DISPLAY_VER(display) >= 20)
>> > +		return BIT(10) | BIT(11);
>> > +	else if (DISPLAY_VER(display) >= 13 && !display->platform.dg2)
>> > +		return BIT(10);
>> 
>> Register contents need to be defined next to the register definition.
>> 
>> But even so, the caller already has the mask we want to change, I
>> already suggested passing that in. What's wrong with that?
>
> The mask used by the caller only contains the bits which the driver
> changes. However I would like to know that writing all the other bits in
> the register also take their effect, reflected by the read-back after the
> write.

Fair enough. The first comment still stands, let's not hardcode the bits
here inline.

BR,
Jani.


-- 
Jani Nikula, Intel