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Message-ID: <31f116f6-a6b7-1241-83bc-96c31e718f3f@linaro.org>
Date: Tue, 25 Apr 2023 10:54:47 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Marijn Suijten <marijn.suijten@...ainline.org>,
Abhinav Kumar <quic_abhinavk@...cinc.com>
Cc: Rob Clark <robdclark@...il.com>, Sean Paul <sean@...rly.run>,
David Airlie <airlied@...il.com>,
Daniel Vetter <daniel@...ll.ch>,
~postmarketos/upstreaming@...ts.sr.ht,
AngeloGioacchino Del Regno
<angelogioacchino.delregno@...ainline.org>,
Konrad Dybcio <konrad.dybcio@...aro.org>,
Martin Botka <martin.botka@...ainline.org>,
Jami Kettunen <jami.kettunen@...ainline.org>,
Jordan Crouse <jordan@...micpenguin.net>,
linux-arm-msm@...r.kernel.org, dri-devel@...ts.freedesktop.org,
freedreno@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 3/3] drm/msm/dpu: Pass catalog pointers directly from
RM instead of IDs
On 25/04/2023 10:16, Marijn Suijten wrote:
> On 2023-04-24 16:23:17, Abhinav Kumar wrote:
>>
>>
>> On 4/24/2023 3:54 PM, Dmitry Baryshkov wrote:
>>> On Tue, 25 Apr 2023 at 01:03, Marijn Suijten
>>> <marijn.suijten@...ainline.org> wrote:
>>>>
>>>> On 2023-04-21 16:25:15, Abhinav Kumar wrote:
>>>>>
>>>>>
>>>>> On 4/21/2023 1:53 PM, Marijn Suijten wrote:
>>>>>> The Resource Manager already iterates over all available blocks from the
>>>>>> catalog, only to pass their ID to a dpu_hw_xxx_init() function which
>>>>>> uses an _xxx_offset() helper to search for and find the exact same
>>>>>> catalog pointer again to initialize the block with, fallible error
>>>>>> handling and all.
>>>>>>
>>>>>> Instead, pass const pointers to the catalog entries directly to these
>>>>>> _init functions and drop the for loops entirely, saving on both
>>>>>> readability complexity and unnecessary cycles at boot.
>>>>>>
>>>>>> Signed-off-by: Marijn Suijten <marijn.suijten@...ainline.org>
>>>>>> Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
>>>>>
>>>>> Overall, a nice cleanup!
>>>>>
>>>>> One comment below.
>>>>>
>>>>>> ---
>>>>>> drivers/gpu/drm/msm/disp/dpu1/dpu_hw_ctl.c | 37 +++++----------------
>>>>>> drivers/gpu/drm/msm/disp/dpu1/dpu_hw_ctl.h | 14 ++++----
>>>>>> drivers/gpu/drm/msm/disp/dpu1/dpu_hw_dsc.c | 32 +++---------------
>>>>>> drivers/gpu/drm/msm/disp/dpu1/dpu_hw_dsc.h | 11 +++----
>>>>>> drivers/gpu/drm/msm/disp/dpu1/dpu_hw_dspp.c | 38 ++++-----------------
>>>>>> drivers/gpu/drm/msm/disp/dpu1/dpu_hw_dspp.h | 12 +++----
>>>>>> drivers/gpu/drm/msm/disp/dpu1/dpu_hw_interrupts.h | 2 +-
>>>>>> drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.c | 40 ++++++-----------------
>>>>>> drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.h | 12 +++----
>>>>>> drivers/gpu/drm/msm/disp/dpu1/dpu_hw_lm.c | 38 ++++-----------------
>>>>>> drivers/gpu/drm/msm/disp/dpu1/dpu_hw_lm.h | 10 +++---
>>>>>> drivers/gpu/drm/msm/disp/dpu1/dpu_hw_merge3d.c | 33 +++----------------
>>>>>> drivers/gpu/drm/msm/disp/dpu1/dpu_hw_merge3d.h | 14 ++++----
>>>>>> drivers/gpu/drm/msm/disp/dpu1/dpu_hw_pingpong.c | 33 +++----------------
>>>>>> drivers/gpu/drm/msm/disp/dpu1/dpu_hw_pingpong.h | 14 ++++----
>>>>>> drivers/gpu/drm/msm/disp/dpu1/dpu_hw_sspp.c | 39 ++++------------------
>>>>>> drivers/gpu/drm/msm/disp/dpu1/dpu_hw_sspp.h | 12 +++----
>>>>>> drivers/gpu/drm/msm/disp/dpu1/dpu_hw_vbif.c | 33 +++----------------
>>>>>> drivers/gpu/drm/msm/disp/dpu1/dpu_hw_vbif.h | 11 +++----
>>>>>> drivers/gpu/drm/msm/disp/dpu1/dpu_hw_wb.c | 33 ++++---------------
>>>>>> drivers/gpu/drm/msm/disp/dpu1/dpu_hw_wb.h | 11 +++----
>>>>>> drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c | 17 +++++-----
>>>>>> drivers/gpu/drm/msm/disp/dpu1/dpu_rm.c | 18 +++++-----
>>>>>> 23 files changed, 139 insertions(+), 375 deletions(-)
>>>>>>
>>>>>
>>>>> <snipped>
>>>>>
>>>>>> -struct dpu_hw_intf *dpu_hw_intf_init(enum dpu_intf idx,
>>>>>> - void __iomem *addr,
>>>>>> - const struct dpu_mdss_cfg *m)
>>>>>> +struct dpu_hw_intf *dpu_hw_intf_init(const struct dpu_intf_cfg *cfg,
>>>>>> + void __iomem *addr)
>>>>>> {
>>>>>> struct dpu_hw_intf *c;
>>>>>> - const struct dpu_intf_cfg *cfg;
>>>>>> +
>>>>>> + if (cfg->type == INTF_NONE) {
>>>>>> + pr_err("Cannot create interface hw object for INTF_NONE type\n");
>>>>>> + return ERR_PTR(-EINVAL);
>>>>>> + }
>>>>>
>>>>> The caller of dpu_hw_intf_init which is the RM already has protection
>>>>> for INTF_NONE, see below
>>>>>
>>>>> for (i = 0; i < cat->intf_count; i++) {
>>>>> struct dpu_hw_intf *hw;
>>>>> const struct dpu_intf_cfg *intf = &cat->intf[i];
>>>>>
>>>>> if (intf->type == INTF_NONE) {
>>>>> DPU_DEBUG("skip intf %d with type none\n", i);
>>>>> continue;
>>>>> }
>>>>> if (intf->id < INTF_0 || intf->id >= INTF_MAX) {
>>>>> DPU_ERROR("skip intf %d with invalid id\n",
>>>>> intf->id);
>>>>> continue;
>>>>> }
>>>>> hw = dpu_hw_intf_init(intf->id, mmio, cat);
>>>>>
>>>>> So this part can be dropped.
>>>>
>>>> I mainly intended to keep original validation where _intf_offset would
>>>> skip INTF_NONE, and error out. RM init is hence expected to filter out
>>>> INTF_NONE instead of running into that `-EINVAL`, which I maintained
>>>> here.
>>>>
>>>> If you think there won't be another caller of dpu_hw_intf_init, and that
>>>> such validation is hence excessive, I can remove it in a followup v3.
>>>
>>> I'd prefer to see the checks at dpu_rm to be dropped.
>>> dpu_hw_intf_init() (and other dpu_hw_foo_init() functions) should be
>>> self-contained. If they can not init HW block (e.g. because the index
>>> is out of the boundaries), they should return an error.
>>>
>>
>> They already do that today because even without this it will call into
>> _intf_offset() and that will bail out for INTF_NONE.
>>
>> I feel this is a duplicated check because the caller with the loop needs
>> to validate the index before passing it to dpu_hw_intf_init() otherwise
>> the loop will get broken at the first return of the error and rest of
>> the blocks will also not be initialized.
>
> To both: keep in mind that the range-checks we want to remove from
> dpu_rm_init validate the ID (index?) of a block. This check is for the
> *TYPE* of an INTF block, to skip it gracefully if no hardware is mapped
> there. As per the first patch of this series SM6115/QCM2290 only have a
> DSI interface which always sits at ID 1, and ID 0 has its TYPE set to
> INTF_NONE and is skipped.
>
> Hence we _should_ keep the graceful TYPE check in dpu_rm_init() to skip
> calling this function _and assigning it to the rm->hw_intf array_. But
> I can remove the second TYPE check here in dpu_hw_intf_init() if you
> prefer.
We can return NULL from dpu_hw_foo_init(), which would mean that the
block was skipped or is not present.
>
> - Marijn
--
With best wishes
Dmitry
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