Re: [PATCH 6/6] drm/msm/dpu: Update dev core dump to dump registers of sub blocks
From: Abhinav Kumar
Date: Sat Jun 24 2023 - 22:44:46 EST
On 6/24/2023 8:03 AM, Dmitry Baryshkov wrote:
On 24/06/2023 17:17, Abhinav Kumar wrote:
On 6/24/2023 5:07 AM, Dmitry Baryshkov wrote:
On 24/06/2023 03:09, Abhinav Kumar wrote:
On 6/22/2023 5:13 PM, Dmitry Baryshkov wrote:
On 23/06/2023 02:48, Ryan McCann wrote:
Currently, the device core dump mechanism does not dump registers
of sub
blocks within the DSPP, SSPP, DSC, and PINGPONG blocks. Add wrapper
function to dump hardware blocks that contain sub blocks.
Signed-off-by: Ryan McCann <quic_rmccann@xxxxxxxxxxx>
---
drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c | 194
+++++++++++++++++++++++++++-----
1 file changed, 168 insertions(+), 26 deletions(-)
diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
index aa8499de1b9f..9b1b1c382269 100644
--- a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
+++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
@@ -885,6 +885,154 @@ static int dpu_irq_postinstall(struct
msm_kms *kms)
return 0;
}
+static void dpu_kms_mdp_snapshot_add_block(struct msm_disp_state
*disp_state,
+ void __iomem *mmio, void *blk,
+ enum dpu_hw_blk_type blk_type)
No. Such multiplexers add no value to the code. Please inline it.
Not to mention that this patch is hard to review. You both move
existing code and add new features. If it were to go, it should
have been split into two patches: one introducing the multiplexer
and another one adding subblocks.
Ok. we can split this into:
1) adding the multiplexer
2) adding sub-blk parsing support inside the multiplexer
I'd say, drop the multiplexer completely. It adds no value here. It
is only used from dpu_kms_mdp_snapshot(). If the code there was
complex enough, it would have made sense to _split_ the function. But
even in such case there would be no point in having multiplexer. We
do not enumerate block by type.
Can you pls elaborate what you mean by enumerate blk by type?
We do have DPU_HW_BLK_***
Did you mean sub-blk?
+{
+ u32 base;
+
+ switch (blk_type) {
+ case DPU_HW_BLK_TOP:
+ {
+ struct dpu_mdp_cfg *top = (struct dpu_mdp_cfg *)blk;
+
+ if (top->features & BIT(DPU_MDP_PERIPH_0_REMOVED)) {
+ msm_disp_snapshot_add_block(disp_state, MDP_PERIPH_TOP0,
+ mmio + top->base, "top");
+ msm_disp_snapshot_add_block(disp_state, top->len -
MDP_PERIPH_TOP0_END,
+ mmio + top->base + MDP_PERIPH_TOP0_END,
+ "top_2");
+ } else {
+ msm_disp_snapshot_add_block(disp_state, top->len,
mmio + top->base, "top");
+ }
+ break;
+ }
+ case DPU_HW_BLK_LM:
+ {
+ struct dpu_lm_cfg *mixer = (struct dpu_lm_cfg *)blk;
+
+ msm_disp_snapshot_add_block(disp_state, mixer->len, mmio
+ mixer->base, "%s",
+ mixer->name);
+ break;
+ }
+ case DPU_HW_BLK_CTL:
+ {
+ struct dpu_ctl_cfg *ctl = (struct dpu_ctl_cfg *)blk;
+
+ msm_disp_snapshot_add_block(disp_state, ctl->len, mmio +
ctl->base, "%s",
+ ctl->name);
+ break;
+ }
+ case DPU_HW_BLK_INTF:
+ {
+ struct dpu_intf_cfg *intf = (struct dpu_intf_cfg *)blk;
+
+ msm_disp_snapshot_add_block(disp_state, intf->len, mmio +
intf->base, "%s",
+ intf->name);
+ break;
+ }
+ case DPU_HW_BLK_WB:
+ {
+ struct dpu_wb_cfg *wb = (struct dpu_wb_cfg *)blk;
+
+ msm_disp_snapshot_add_block(disp_state, wb->len, mmio +
wb->base, "%s",
+ wb->name);
+ break;
+ }
+ case DPU_HW_BLK_SSPP:
+ {
+ struct dpu_sspp_cfg *sspp_block = (struct dpu_sspp_cfg
*)blk;
+ const struct dpu_sspp_sub_blks *sblk = sspp_block->sblk;
+
+ base = sspp_block->base;
+
+ msm_disp_snapshot_add_block(disp_state, sspp_block->len,
mmio + base, "%s",
+ sspp_block->name);
+
+ if (sspp_block->features & BIT(DPU_SSPP_SCALER_QSEED3) ||
+ sspp_block->features &
BIT(DPU_SSPP_SCALER_QSEED3LITE) ||
+ sspp_block->features & BIT(DPU_SSPP_SCALER_QSEED4))
+ msm_disp_snapshot_add_block(disp_state,
sblk->scaler_blk.len,
+ mmio + base + sblk->scaler_blk.base,
"%s_%s",
+ sspp_block->name,
sblk->scaler_blk.name);
Actually, it would be better to:
- drop name from all sblk instances (and use known string instead
of the sblk name here)
- Use sblk->foo_blk.len to check if it should be printed or not.
No, I dont agree. If we drop the names from the sub_blk in the
catalog, we will end up using "sub_blk_name" string here in the code
to indicate which blk that is in the dump.
If we add more sub_blks in the catalog in the future we need to keep
changing the code over here. Thats not how it should be.
Leaving the names in the catalog ensures that this code wont change
and only catalog changes when we add a new sub_blk either for an
existing or new chipset.
catalog is indicating the new blk, and dumping code just prints it.
with your approach, dumping code will or can keep changing with
chipsets or sub_blks. Thats not how it should be.
Well, we do not enumerate sub-blocks in any way, they are not
indexed. So even with sblk->blk.name in place, adding new sub-block
would require adding new code here. That's why I wrote that the
calling code knows which sub-block it refers to.
Today, unfortunately each sub_blk type is different so we have to do
this case by case.
Ideally, this should have just been
-> print main blk
-> print all sub-blks of the main blk
Without having to handle each main blk's sub-blks separately.
That way the dumping code would have remained generic without having
to do even the multiplexer in the first place.
Need to explore if somehow we can come up with a generic sub-blk
struct and make this possible. Then this code will become much easier
and what I am saying will make total sense.
In such case, yes. However I'd warn about having a generic array of
subblocks. Having named subblock entries might complicate snapshotting,
but it makes the rest of the DPU driver smaller.
Need to explore this. But not immediately.
Even without that, conceptually these sub-blk names are reflecting
whats in our software document. So its not a random name but reflects
the actual sub-blk name from the hardware.
Yes
So this belongs in the catalog.
But the sub-block field already has a correct name: scaler_blk, csc_blk,
etc. Having both sub-block field name and the .name inside results in
kind of duplication, which seems unnecessary to me.
No, there is a difference and not duplicated. One is the name of the
struct so it can really be anything and doesnt need to match the hw doc
name. But the other is the string name which we can give exactly to
match software interface doc and makes parsing such a dump much much easier.
One point I dont see you have considered is the block index of the sub_blk.
Today, yes I see only a "pcc" or a "dither" etc
What if there are two PCCs or two dithers.
Then their names can just be "pcc_0" and "pcc_1" or "dither_0" and
"dither_1".
Having name gives us the ability to easily incorporate even unsequential
indices.
For example, every sspp's name today is not sequential. it can be
"sspp_3" then "sspp_8" etc
By having names reflect the correct indices, dumping code becomes less
complex as the catalog will still have the right names as dumping code
will just use that.
Dumping code should not change or know whats the name of each block.
It should just use whats in the catalog. thats why even conceptually I
am not okay with your idea.
Dumping code itself (msm_disp_snapshot_*) doesn't. But the caller code
knows what is the subblock.
But this is the dumping code because we are adding which blocks to dump.
Let me pick a definition from the patch:
static const struct dpu_dspp_sub_blks msm8998_dspp_sblk = {
.pcc = {.name = "pcc", .id = DPU_DSPP_PCC, .base = 0x1700,
.len = 0x90, .version = 0x10007},
};
the "pcc" is repeated three times. When the code looks at this block, it
already knows that it is a PCC block.
I agree with you about the "id" though. From what I can see in this
patch, "id" is not used and we can drop that. So that change from your
series is fine with me.
But the pcc is the struct name which doesnt really need to reflect the
hw name but the name field of the PCC should IMO.
Compare this with:
static const struct dpu_dspp_sub_blks msm8998_dspp_sblk = {
.pcc = {
.base = 0x1700,
.len = 0x90,
.version = 0x10007,
},
};
Nothing is repeated, but we still know that this is the DSPPn_PCC
sub-block description.
Calling code does:
u32 base;
base = ctx->cap->sblk->pcc.base;
Let me extract the relevant code (skipping all the conditions for now):
msm_disp_snapshot_add_block(disp_state, sspp_block->len, mmio + base,
"%s",
sspp_block->name);
if (have_scaler)
msm_disp_snapshot_add_block(disp_state, sblk->scaler_blk.len,
mmio + base + sblk->scaler_blk.base, "%s_%s",
sspp_block->name, sblk->scaler_blk.name);
if (have_csc)
msm_disp_snapshot_add_block(disp_state, sblk->csc_blk.len,
mmio + base + sblk->csc_blk.base, "%s_%s",
sspp_block->name, sblk->csc_blk.name);
Consider adding new sub-block, "baz". We would still require manual
addition of the following code:
msm_disp_snapshot_add_block(disp_state, sblk->baz_blk.len,
mmio + base + sblk->baz_blk.base, "%s_%s",
sspp_block->name, sblk->baz_blk.name);
Compare this with:
msm_disp_snapshot_add_block(disp_state, sblk->baz_blk.len,
mmio + base + sblk->baz_blk.base, "%s_baz",
sspp_block->name);
Basically you are saying why not make the one line change here instead
of using the name from the catalog.
I think it will be better to use from the catalog for the reason I
wrote above that dumping code should just "use" the catalog's
information and not become a catalog itself.
You are not saving much by dropping the sub-blk name from catalog anyway.
Moreover, if we follow the style of dpu_kms_mdp_snapshot() (which
doesn't use name), it should be:
msm_disp_snapshot_add_block(disp_state, sblk->baz_blk.len,
mmio + base + sblk->baz_blk.base, "sspp%d_baz",
idx);
tbh, after looking at this series, it made me think why I didnt use
the name from the catalog even for the dpu_kms_mdp_snapshot()
<snipped>