[PATCH RFC 4/8] drm/msm: adreno: dynamically generate GMU bw table

[Dmitry Baryshkov]

On Fri, Nov 15, 2024 at 10:11:09AM +0100, Neil Armstrong wrote:
> On 15/11/2024 08:24, Dmitry Baryshkov wrote:
> > On Wed, Nov 13, 2024 at 04:48:30PM +0100, Neil Armstrong wrote:
> > > The Adreno GPU Management Unit (GMU) can also scale the ddr
> > > bandwidth along the frequency and power domain level, but for
> > > now we statically fill the bw_table with values from the
> > > downstream driver.
> > > 
> > > Only the first entry is used, which is a disable vote, so we
> > > currently rely on scaling via the linux interconnect paths.
> > > 
> > > Let's dynamically generate the bw_table with the vote values
> > > previously calculated from the OPPs.
> > 
> > Nice to see this being worked upon. I hope the code can is generic
> > enough so that we can use it from other adreno_foo_build_bw_table()
> > functions.
> 
> I would hope so, but I don't have the HW to properly test it on those
> platforms.

Welcome to the club^W Lab.

> > > Those entried will then be used by the GMU when passing the
> > > appropriate bandwidth level when voting for a gpu frequency.
> > > 
> > > Signed-off-by: Neil Armstrong <neil.armstrong at linaro.org>
> > > ---
> > >   drivers/gpu/drm/msm/adreno/a6xx_hfi.c | 48 +++++++++++++++++++++++++++--------
> > >   1 file changed, 37 insertions(+), 11 deletions(-)
> > > 
> > > diff --git a/drivers/gpu/drm/msm/adreno/a6xx_hfi.c b/drivers/gpu/drm/msm/adreno/a6xx_hfi.c
> > > index cb8844ed46b29c4569d05eb7a24f7b27e173190f..9a89ba95843e7805d78f0e5ddbe328677b6431dd 100644
> > > --- a/drivers/gpu/drm/msm/adreno/a6xx_hfi.c
> > > +++ b/drivers/gpu/drm/msm/adreno/a6xx_hfi.c
> > > @@ -596,22 +596,48 @@ static void a730_build_bw_table(struct a6xx_hfi_msg_bw_table *msg)
> > >   	msg->cnoc_cmds_data[1][0] = 0x60000001;
> > >   }
> > > -static void a740_build_bw_table(struct a6xx_hfi_msg_bw_table *msg)
> > > +static void a740_generate_bw_table(struct adreno_gpu *adreno_gpu, struct a6xx_gmu *gmu,
> > > +				   struct a6xx_hfi_msg_bw_table *msg)
> > >   {
> > > -	msg->bw_level_num = 1;
> > > +	const struct a6xx_info *info = adreno_gpu->info->a6xx;
> > > +	unsigned int i, j;
> > > -	msg->ddr_cmds_num = 3;
> > >   	msg->ddr_wait_bitmask = 0x7;
> > > -	msg->ddr_cmds_addrs[0] = cmd_db_read_addr("SH0");
> > > -	msg->ddr_cmds_addrs[1] = cmd_db_read_addr("MC0");
> > > -	msg->ddr_cmds_addrs[2] = cmd_db_read_addr("ACV");
> > > +	for (i = 0; i < 3; i++) {
> > > +		if (!info->bcm[i].name)
> > > +			break;
> > > +		msg->ddr_cmds_addrs[i] = cmd_db_read_addr(info->bcm[i].name);
> > > +	}
> > > +	msg->ddr_cmds_num = i;
> > > -	msg->ddr_cmds_data[0][0] = 0x40000000;
> > > -	msg->ddr_cmds_data[0][1] = 0x40000000;
> > > -	msg->ddr_cmds_data[0][2] = 0x40000000;
> > > +	for (i = 0; i < gmu->nr_gpu_bws; ++i)
> > > +		for (j = 0; j < msg->ddr_cmds_num; j++)
> > > +			msg->ddr_cmds_data[i][j] = gmu->gpu_bw_votes[i][j];
> > > +	msg->bw_level_num = gmu->nr_gpu_bws;
> > > +}
> > > +
> > > +static void a740_build_bw_table(struct adreno_gpu *adreno_gpu, struct a6xx_gmu *gmu,
> > > +				struct a6xx_hfi_msg_bw_table *msg)
> > > +{
> > > +	if ((adreno_gpu->info->quirks & ADRENO_QUIRK_GMU_BW_VOTE) && gmu->nr_gpu_bws) {
> > > +		a740_generate_bw_table(adreno_gpu, gmu, msg);
> > > +	} else {
> > 
> > Why do we need a fallback code here?
> 
> Because at this particular commit, it would generate an invalid table, I should probably remove the fallback at the end

Or move this to a generic code that generates a table if there is no bw
data (like there is none for older platforms with the current DTs).

> 
> > 
> > > +		msg->bw_level_num = 1;
> > > -	/* TODO: add a proper dvfs table */
> > > +		msg->ddr_cmds_num = 3;
> > > +		msg->ddr_wait_bitmask = 0x7;
> > > +
> > > +		msg->ddr_cmds_addrs[0] = cmd_db_read_addr("SH0");
> > > +		msg->ddr_cmds_addrs[1] = cmd_db_read_addr("MC0");
> > > +		msg->ddr_cmds_addrs[2] = cmd_db_read_addr("ACV");
> > > +
> > > +		msg->ddr_cmds_data[0][0] = 0x40000000;
> > > +		msg->ddr_cmds_data[0][1] = 0x40000000;
> > > +		msg->ddr_cmds_data[0][2] = 0x40000000;
> > > +
> > > +		/* TODO: add a proper dvfs table */
> > 
> > I think TODO is unapplicable anymore.
> > 
> > > +	}
> > >   	msg->cnoc_cmds_num = 1;
> > >   	msg->cnoc_wait_bitmask = 0x1;
> > > @@ -691,7 +717,7 @@ static int a6xx_hfi_send_bw_table(struct a6xx_gmu *gmu)
> > >   	else if (adreno_is_a730(adreno_gpu))
> > >   		a730_build_bw_table(msg);
> > >   	else if (adreno_is_a740_family(adreno_gpu))
> > > -		a740_build_bw_table(msg);
> > > +		a740_build_bw_table(adreno_gpu, gmu, msg);
> > >   	else
> > >   		a6xx_build_bw_table(msg);
> > > 
> > > -- 
> > > 2.34.1
> > > 
> > 
> 

-- 
With best wishes
Dmitry