Re: [PATCH 0/5] Add UFS support for SM8750

[Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>]

On 10.02.2025 12:08 PM, Nitin Rawat wrote:
> 
> 
> On 2/10/2025 3:43 PM, Manivannan Sadhasivam wrote:
>> + Can (for the MCQ query)
>>
>> On Mon, Feb 10, 2025 at 10:39:04AM +0100, neil.armstrong@linaro.org wrote:
>>> On 09/02/2025 16:21, Manivannan Sadhasivam wrote:
>>>> On Fri, Feb 07, 2025 at 11:47:12PM +0100, Konrad Dybcio wrote:
>>>>> On 13.01.2025 10:46 PM, Melody Olvera wrote:
>>>>>> Add UFS support for SM8750 SoCs.
>>>>>>
>>>>>> Signed-off-by: Melody Olvera <quic_molvera@quicinc.com>
>>>>>> ---
>>>>>> Nitin Rawat (5):
>>>>>>         dt-bindings: phy: qcom,sc8280xp-qmp-ufs-phy: Document the SM8750 QMP UFS PHY
>>>>>>         phy: qcom-qmp-ufs: Add PHY Configuration support for SM8750
>>>>>>         dt-bindings: ufs: qcom: Document the SM8750 UFS Controller
>>>>>>         arm64: dts: qcom: sm8750: Add UFS nodes for SM8750 SoC
>>>>>>         arm64: dts: qcom: sm8750: Add UFS nodes for SM8750 QRD and MTP boards
>>>>>
>>>>> You still need the same workaround 8550/8650 have in the UFS driver
>>>>> (UFSHCD_QUIRK_BROKEN_LSDBS_CAP) for it to work reliably, or at least
>>>>> that was the case for me on a 8750 QRD.
>>>>>
>>>>> Please check whether we can make that quirk apply based on ctrl
>>>>> version or so, so that we don't have to keep growing the compatible
>>>>> list in the driver.
>>>>>
>>>>
>>>> That would be a bizarre. When I added the quirk, I was told that it would affect
>>>> only SM8550 and SM8650 (this one I learned later). I'm not against applying the
>>>> quirk based on UFSHC version if the bug is carried forward, but that would be an
>>>> indication of bad design.
>>>
>>> Isn't 8750 capable of using MCQ now ? because this is the whole issue behind
>>> this UFSHCD_QUIRK_BROKEN_LSDBS_CAP, it's supposed to use MCQ by default... but
>>> we don't.
>>>
>>> Is there any news about that ? It's a clear regression against downstream, not
>>> having MCQ makes the UFS driver struggle to reach high bandwidth when the system
>>> is busy because we can't spread the load over all CPUs and we have only single
>>> queue to submit requests.
>>>
>>
>> There are hardware issues on SM8550 and SM8650(?) for the MCQ feature.
>> Apparently, Qcom carries the workaround in downstream, but I got tired of
>> pushing them to upstream the fix(es).
>>
>> Maybe Can Guo can share what is the latest update on this.
>>
>> - Mani
>>
> 
> Hi Mani,
> 
> I have already replied to konrad mail earlier in this thread.
> 
> The LSDBS workaround is only applicable for SM8650 and SM8550.
> SM8750 and onwards doesn't need this WA anymore as it is fixed in HW.

Nitin, you're right. I was hitting another issue and adding that quirk
only randomly changed some timings for it to not manifest

Sorry for the confusion.

Konrad