linux-kernel - Re: [PATCH 3/4] phy: qcom-qmp: Add optional SW reset

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Date:   Mon, 23 Dec 2019 14:30:27 +0530
From:   Manu Gautam <mgautam@...eaurora.org>
To:     Vinod Koul <vkoul@...nel.org>, Can Guo <cang@...eaurora.org>
Cc:     Asutosh Das <asutoshd@...eaurora.org>,
        Kishon Vijay Abraham I <kishon@...com>,
        linux-arm-msm@...r.kernel.org,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Andy Gross <agross@...nel.org>,
        Jeffrey Hugo <jeffrey.l.hugo@...il.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/4] phy: qcom-qmp: Add optional SW reset


On 12/20/2019 1:23 PM, Vinod Koul wrote:
> On 20-12-19, 15:41, Can Guo wrote:
>> On 2019-12-20 15:10, Vinod Koul wrote:
>>> On 20-12-19, 14:00, Can Guo wrote:
>> Hi Vinod
>>
>> We are just removing the no_pcs_sw_reset for 8150, right? Why is it
>> possibly impacting 845 or older paltforms?
>>
>> In future, we will no longer need no_pcs_sw_reset for any newer QCOM UFS
>> PHY designs, as it is only for 845 and older platforms.
>>
>> I am sure QPHY_SW_RESET will be within PHY's address space since 8150.
>> Otherwise, it will be a regression in UFS PHY design. We had a lot of
>> discussion about this on 845 years ago, then design team decided to add
>> it on later platforms, so I don't see a reason to remove it again. :)
>>
>> I am not sure about the other qmp phys, but so long as UFS PHY needs the
>> reset, we need to keep it, as phy-qcom-qmp.c is a common driver. I am
>> not sure if I get your point here. Please correct me I am wrong.
> The argument here is that we are making this UFS specific and we do not
> know if this will be true in future as QMP is a common phy, so adding a
> separate flag helps to keep it independent and to be used in other
> situations.
>
> Thanks

We should just remove no_pcs_sw_reset and let existing code take care
of PHY reset for UFS.
QMP PHY reset for UFS was differently handled earlier compared to USB/PCie
and relied on core for PHY reset. That is not the case with addition of
PCS based sw_reset and this won't change in future. There is no need to
have UFS specific flag in this driver.


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