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

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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.



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@xxxxxxxxxx>
---
  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


+		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







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