Re: [PATCH] drm/i915/display: update BW buddy initialization for LPDDR4 and LPDDR5

["Govindapillai, Vinod" <vinod.govindapillai@intel.com>]

On Fri, 2026-05-29 at 18:20 +0300, Ville Syrjälä wrote:
> On Fri, May 29, 2026 at 04:39:13PM +0300, Jani Nikula wrote:
> > On Thu, 28 May 2026, Vinod Govindapillai
> > <vinod.govindapillai@intel.com> wrote:
> > > Pcode reports the number of subchannels for LPDDR4 and LPDDR5.
> > > But the page mask selection table is based on the channels. So
> > > adjust the number of channels for LPDDR4 and LPDDR5 so that the
> > > correct page mask can be picked. There are two subchannels per
> > > channel.
> > 
> > IMO the parsing of the information belongs in intel_dram.c. If you
> > get
> > subchannels from pcode or where ever, intel_dram.c should figure it
> > out,
> > and store the number of channels in ->num_channels.
> 
> We actually want subchannels for QGV stuff. And that's what modern
> pcode gives us, older pcode gave us channels instead and we convert
> that to subchannels in the QGV code on those platforms. I have a
> patch
> to move the adjustment into intel_dram.c for those platforms so that
> we get consistent data out of intel_dram.c everywhere.
> 
> For this thing here I think the best thing would be to change the
> table to use subchannels instead. Looks like Vinod didn't file the
> Bspec
> issue asking for the table to be updated there, so I just did that.

Oh.. sorry..  I suggested a wrong code yesterday on jira to be tried by
the customer. So wanted to fix that! Will use the updated table when it
is updated.

BR
Vinod

>