linux-kernel - Re: [PATCH v5 2/7] scsi: ufs-qcom: Add reset control support for host controller

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Date:   Tue, 17 Dec 2019 15:10:29 +0800
From:   cang@...eaurora.org
To:     Vinod Koul <vkoul@...nel.org>
Cc:     Jeffrey Hugo <jeffrey.l.hugo@...il.com>, asutoshd@...eaurora.org,
        nguyenb@...eaurora.org, Rajendra Nayak <rnayak@...eaurora.org>,
        linux-scsi@...r.kernel.org, kernel-team@...roid.com,
        saravanak@...gle.com, salyzyn@...gle.com,
        Andy Gross <agross@...nel.org>,
        Alim Akhtar <alim.akhtar@...sung.com>,
        Avri Altman <avri.altman@....com>,
        Pedro Sousa <pedrom.sousa@...opsys.com>,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        "open list:ARM/QUALCOMM SUPPORT" <linux-arm-msm@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v5 2/7] scsi: ufs-qcom: Add reset control support for host
 controller

On 2019-12-17 12:13, Vinod Koul wrote:
> Hi Can,
> 
> On 17-12-19, 08:37, cang@...eaurora.org wrote:
>> On 2019-12-17 03:12, Jeffrey Hugo wrote:
>> > On Mon, Dec 16, 2019 at 12:05 PM Vinod Koul <vkoul@...nel.org> wrote:
>> > >
>> > > Hi Can,
>> > >
>> > > On 14-11-19, 22:09, Can Guo wrote:
>> > > > Add reset control for host controller so that host controller can be reset
>> > > > as required in its power up sequence.
>> > >
>> > > I am seeing a regression on UFS on SM8150-mtp with this patch. I think
>> > > Jeff is seeing same one lenove laptop on 8998.
>> >
>> > Confirmed.
>> >
>> > >
>> > > 845 does not seem to have this issue and only thing I can see is
>> > > that on
>> > > sm8150 and 8998 we define reset as:
>> > >
>> > >                         resets = <&gcc GCC_UFS_BCR>;
>> > >                         reset-names = "rst";
>> > >
>> 
>> Hi Jeffrey and Vinod,
>> 
>> Thanks for reporting this. May I know what kind of regression do you 
>> see on
>> 8150 and 8998?
>> BTW, do you have reset control for UFS PHY in your DT?
>> See 71278b058a9f8752e51030e363b7a7306938f64e.
>> 
>> FYI, we use reset control on all of our platforms and it is
>> a must during our power up sequence.
> 
> Yes we do have this and additionally both the DTS describe a 'rst' 
> reset
> and this patch tries to use this.
> 
> Can you please tell me which platform this was tested on how the reset
> was described in DT
> 
> Thanks

Hi Vinod,

If you are using the 8998's DT present on upstream, you may also need to 
enable
device reset on your platform. (We usually do a device reset before call 
ufshcd_hba_enable())
Given that 845 works fine, it may be the difference you have with 845. 
845 has device
reset support ready in upstream code, you can check sdm845-mtp.dts.
It is same for 8150, which is a lack of device reset support in upstream 
code base.

To enable UFS device reset, please see
1. 
https://lore.kernel.org/linux-arm-msm/20190828191756.24312-4-bjorn.andersson@linaro.org/
2. 53a5372ce326116f3e3d3f1d701113b2542509f4

FYI, I tested the patch on 8250 and its family platforms. In my build, I 
ported
change in #2 to my code base (in your case, make change to
drivers/pinctrl/qcom/pinctrl-msm8998.c) and enable the GPIO in DT like 
sdm845-mtp.dts

         reset-gpios = <&tlmm 150 GPIO_ACTIVE_LOW>;

Thanks