On 16/11/2022 12:29, Abhinav Kumar wrote:
On 11/16/2022 1:18 AM, Dmitry Baryshkov wrote:On 16/11/2022 11:30, Abhinav Kumar wrote:On 11/16/2022 12:19 AM, Dmitry Baryshkov wrote:On 16/11/2022 10:50, Abhinav Kumar wrote:On 11/4/2022 6:03 AM, Dmitry Baryshkov wrote:On sm8450 a register block was removed from MDP TOP. Accessing it duringsnapshotting results in NoC errors / immediate reboot. Skip accessing these registers during snapshot. Tested-by: Vinod Koul <vkoul@xxxxxxxxxx> Reviewed-by: Vinod Koul <vkoul@xxxxxxxxxx> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>I am confused with both the ordering and the split of this patch.You have defined DPU_MDP_PERIPH_0_REMOVED in the catalog header file in this patch but used it in the next.But you also have code in this patch which relies on setting of this bit.So if this patch is taken without the next, it will still crash.It will not crash if this patch is taken without the next one. Without the next patch the DPU driver will not match and bind against the qcom,sm8450-dpu device.Ah okay, I just now saw that you have the compatible change also in the next patch.So, the ordering is quite logical from my point of view: - add support for all the features required for the device - add the device compat string & catalog entryRather, you should combine the define part of this patch to the next patch in the series https://patchwork.freedesktop.org/patch/510114/?series=108883&rev=3 , then move that one in front of this patch.No. This way we'll have a state (after adding the next patch) when the sm8450 support is enabled, but the top-hole is not handled, leading to a crash.What if you split the compatible to a separate patch like what SM8350 did.https://patchwork.freedesktop.org/patch/511659/?series=110924&rev=1So, we have hw catalog changes ---> snapshot fix ---> add the compatible.I don't see any good reason to do this. Adding a define without backing implementation is a bad idea in my opinion.The define is used in two places today. First in the catalog and second in the snapshot (which is your change).Even with the split i am suggesting the define and usage will be together.In fact, in my opinion thats more coherent because you defined the macro, used it to show that sm8450 has this TOP_HOLE.Then, you are using the hw->caps which will be set in the previous patch to avoid that region in the snapshot.The good reason to do it this way is that, with this current ordering of patch, this patch is essentially a dummy patch because technically no chipset has set this capability.
It's not dummy, because it clearly shows, what really is beyond this capability. A feature without a backing implementation would be a dummy patch (even if it's mentioned in the hw catalog entry).
Just a simple check. If we use a guillotine and cut the patch series in the middle, which one will make more sense:
- #define DPU_MDP_TOP_UGLY add DPU_MDP_TOP_UGLY to sdm999's features - #define DPU_MDP_TOP_UGLY add an implementation of DPU_MDP_TOP_UGLY describing what it doesWith the first approach the MDP_TOP_UGLY is an ugly define without any particular meaning. Mentioning it in the hw_catalog doesn't bring us any additional information (in other words, what does it mean that sdm999 has MDP_TOP_UGLY feature?).
The second approach doesn't bind any chipset to use MDP_TOP_UGLY. But knowing the implementation, one can check whether it applies to his chipset or not.
Yes, I must admit, this case is a little bit odd. Regularly I'd have added the sm8450's compat string and catalog entries, then I'd have populated the catalog with new features one by one (using implementation + define + hw_catalog patch), like we do e.g. for DSC, WB, DSPP_sub_flush, etc. In this particular case, sm8450 will not work without PERIPH_0_REMOVED, as the first DSI underrun, which can easily happen while turning on the INTF, will reboot the board.
But if you follow the order i am suggesting, it actually has more meaning because we know sm8450 has set it in its caps before you use it.Regarding splitting the hw_catalog and compat. I have always considered the hw catalog entry as of_device_id.data. In other words, a devices' match data, which makes a little sense without compat entry.With the current approach each patch is atomic, it changes single point or adds a single feature, etc.That will make both of us happy?So that its much more coherent that you defined DPU_MDP_PERIPH_0_REMOVED both in the catalog header and used it in the catalog.c file and the in the next change you used the caps to avoid touching that register.I'd say it's rather strange way. When I see a define/feature addition, I'd prefer to seethe implementation too.Regarding the TOP hole itself, I need one day to investigate this. I am waiting for permissions to the documentation.If i cannot get access by the time you have re-ordered this, I will ack this once the reorder is done within a day.For the reference: [1][1] https://git.codelinaro.org/clo/la/platform/vendor/opensource/display-drivers/-/commit/f9ff8af5b640147f3651c23551c60f81f62874b1--- drivers/gpu/drm/msm/disp/dpu1/dpu_hw_catalog.h | 1 + drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c | 11 +++++++++-- 2 files changed, 10 insertions(+), 2 deletions(-)diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_catalog.h b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_catalog.hindex 38aa38ab1568..4730f8268f2a 100644 --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_catalog.h +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_catalog.h @@ -92,6 +92,7 @@ enum { DPU_MDP_UBWC_1_0, DPU_MDP_UBWC_1_5, DPU_MDP_AUDIO_SELECT, + DPU_MDP_PERIPH_0_REMOVED, DPU_MDP_MAX };diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.cindex f3660cd14f4f..95d8765c1c53 100644 --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c@@ -927,8 +927,15 @@ static void dpu_kms_mdp_snapshot(struct msm_disp_state *disp_state, struct msm_kmsm_disp_snapshot_add_block(disp_state, cat->wb[i].len, dpu_kms->mmio + cat->wb[i].base, "wb_%d", i); - msm_disp_snapshot_add_block(disp_state, cat->mdp[0].len, - dpu_kms->mmio + cat->mdp[0].base, "top");+ if (dpu_kms->hw_mdp->caps->features & BIT(DPU_MDP_PERIPH_0_REMOVED)) {+ msm_disp_snapshot_add_block(disp_state, 0x380, + dpu_kms->mmio + cat->mdp[0].base, "top");+ msm_disp_snapshot_add_block(disp_state, cat->mdp[0].len - 0x3a8,+ dpu_kms->mmio + cat->mdp[0].base + 0x3a8, "top_2"); + } else { + msm_disp_snapshot_add_block(disp_state, cat->mdp[0].len, + dpu_kms->mmio + cat->mdp[0].base, "top"); + } pm_runtime_put_sync(&dpu_kms->pdev->dev); }
-- With best wishes Dmitry
