linux-kernel - Re: [PATCH RFC 6/8] drm/msm: adreno: enable GMU bandwidth for A740 and A750

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Message-ID: <p4pqswgaxbx2aji6y5v2qngn3xp4gdlruthhbzpb4cgfs2earz@mo7zbsgqwc4b>
Date: Fri, 15 Nov 2024 16:39:11 +0200
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Neil Armstrong <neil.armstrong@...aro.org>
Cc: Akhil P Oommen <quic_akhilpo@...cinc.com>, 
	Viresh Kumar <vireshk@...nel.org>, Nishanth Menon <nm@...com>, Stephen Boyd <sboyd@...nel.org>, 
	"Rafael J. Wysocki" <rafael@...nel.org>, Rob Clark <robdclark@...il.com>, Sean Paul <sean@...rly.run>, 
	Konrad Dybcio <konradybcio@...nel.org>, Abhinav Kumar <quic_abhinavk@...cinc.com>, 
	Marijn Suijten <marijn.suijten@...ainline.org>, David Airlie <airlied@...il.com>, 
	Simona Vetter <simona@...ll.ch>, Bjorn Andersson <andersson@...nel.org>, 
	Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, 
	Conor Dooley <conor+dt@...nel.org>, Connor Abbott <cwabbott0@...il.com>, linux-pm@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org, dri-devel@...ts.freedesktop.org, 
	freedreno@...ts.freedesktop.org, devicetree@...r.kernel.org
Subject: Re: [PATCH RFC 6/8] drm/msm: adreno: enable GMU bandwidth for A740
 and A750

On Fri, Nov 15, 2024 at 10:20:01AM +0100, Neil Armstrong wrote:
> On 15/11/2024 08:33, Dmitry Baryshkov wrote:
> > On Wed, Nov 13, 2024 at 04:48:32PM +0100, Neil Armstrong wrote:
> > > Now all the DDR bandwidth voting via the GPU Management Unit (GMU)
> > > is in place, let's declare the Bus Control Modules (BCMs) and
> > 
> > s/let's //g
> > 
> > > it's parameters in the GPU info struct and add the GMU_BW_VOTE
> > > quirk to enable it.
> > 
> > Can we define a function that checks for info.bcm[0].name isntead of
> > adding a quirk?
> 
> Probably, I'll need ideas to how design this better, perhaps a simple
> capability bitfield in a6xx_info ?

I'm not sure if I follow the question. I think it's better to check for
the presens of the data rather than having a separate 'cap' bit in
addition to that data.

> There's other feature that are lacking, like ACD or BCL which are not supported
> on all a6xx/a7xx gpus.

Akhil is currently working on ACD, as you have seen from the patches.

> 
> > 
> > > 
> > > Signed-off-by: Neil Armstrong <neil.armstrong@...aro.org>
> > > ---
> > >   drivers/gpu/drm/msm/adreno/a6xx_catalog.c | 26 ++++++++++++++++++++++++--
> > >   1 file changed, 24 insertions(+), 2 deletions(-)
> > > 
> > > diff --git a/drivers/gpu/drm/msm/adreno/a6xx_catalog.c b/drivers/gpu/drm/msm/adreno/a6xx_catalog.c
> > > index 0c560e84ad5a53bb4e8a49ba4e153ce9cf33f7ae..014a24256b832d8e03fe06a6516b5348a5c0474a 100644
> > > --- a/drivers/gpu/drm/msm/adreno/a6xx_catalog.c
> > > +++ b/drivers/gpu/drm/msm/adreno/a6xx_catalog.c
> > > @@ -1379,7 +1379,8 @@ static const struct adreno_info a7xx_gpus[] = {
> > >   		.inactive_period = DRM_MSM_INACTIVE_PERIOD,
> > >   		.quirks = ADRENO_QUIRK_HAS_CACHED_COHERENT |
> > >   			  ADRENO_QUIRK_HAS_HW_APRIV |
> > > -			  ADRENO_QUIRK_PREEMPTION,
> > > +			  ADRENO_QUIRK_PREEMPTION |
> > > +			  ADRENO_QUIRK_GMU_BW_VOTE,
> > >   		.init = a6xx_gpu_init,
> > >   		.zapfw = "a740_zap.mdt",
> > >   		.a6xx = &(const struct a6xx_info) {
> > > @@ -1388,6 +1389,16 @@ static const struct adreno_info a7xx_gpus[] = {
> > >   			.pwrup_reglist = &a7xx_pwrup_reglist,
> > >   			.gmu_chipid = 0x7020100,
> > >   			.gmu_cgc_mode = 0x00020202,
> > > +			.bcm = {
> > > +				[0] = { .name = "SH0", .buswidth = 16 },
> > > +				[1] = { .name = "MC0", .buswidth = 4 },
> > > +				[2] = {
> > > +					.name = "ACV",
> > > +					.fixed = true,
> > > +					.perfmode = BIT(3),
> > > +					.perfmode_bw = 16500000,
> > 
> > Is it a platform property or GPU / GMU property? Can expect that there
> > might be several SoCs having the same GPU, but different perfmode_bw
> > entry?
> 
> I presume this is SoC specific ? But today the XXX_build_bw_table() are
> already SoC specific, so where should this go ?

XXX_build_bw_table() are GPU-specific. There are cases of several SoCs
sharing the same GPU on them.

> Downstream specifies this in the adreno-gpulist.h, which is the equivalent
> here.

-- 
With best wishes
Dmitry