From: nguyenb@codeaurora.org
To: Avri Altman <Avri.Altman@wdc.com>
Cc: cang@codeaurora.org, asutoshd@codeaurora.org,
martin.petersen@oracle.com, linux-scsi@vger.kernel.org,
linux-arm-msm@vger.kernel.org,
Alim Akhtar <alim.akhtar@samsung.com>,
"James E.J. Bottomley" <jejb@linux.ibm.com>,
Stanley Chu <stanley.chu@mediatek.com>,
Bean Huo <beanhuo@micron.com>,
Bart Van Assche <bvanassche@acm.org>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v1 1/1] scsi: ufshcd: Properly set the device Icc Level
Date: Mon, 14 Sep 2020 09:34:43 -0700 [thread overview]
Message-ID: <e1b4e9f5eab891fa6615e7a4b2ed29e6@codeaurora.org> (raw)
In-Reply-To: <BY5PR04MB6705A865E35CDA367249DC4EFC270@BY5PR04MB6705.namprd04.prod.outlook.com>
On 2020-09-10 03:02, Avri Altman wrote:
>>
>> On 2020-08-31 18:19, Bao D. Nguyen wrote:
>> > UFS version 3.0 and later devices require Vcc and Vccq power supplies
>> > with Vccq2 being optional. While earlier UFS version 2.0 and 2.1
>> > devices, the Vcc and Vccq2 are required with Vccq being optional.
>> > Check the required power supplies used by the device
>> > and set the device's supported Icc level properly.
> Practically you are correct - most flash vendors moved in UFS3.1 to
> 1.2 supply instead of 1.8.
> However, the host should provide all 3 supplies to the device because -
> a) A flash vendor might want to still use 1.8 in its UFS3.1 device, and
> b) We should allow a degenerated configurations, e.g. 3.1 devices,
> that are degenerated to 2.1 or 2.2
Thank you for your comment.
The host can provide all 3 power supplies. However, the change is to
ensure
we do not exit early and fail to properly set the Icc level because the
optional power
supply is not provided.
>
> That said, I think we can entirely remove the check in the beginning
> of the function,
> But not because the spec allows it, but because each supply is
> explicitly checked later on,
> before reading its applicable max current entry in the power
> descriptor.
We need these checks to prevent NULL pointer access subsequently in this
function.
> Thanks,
> Avri
next prev parent reply other threads:[~2020-09-14 16:35 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-01 1:19 [PATCH v1 1/1] scsi: ufshcd: Properly set the device Icc Level Bao D. Nguyen
2020-09-10 1:28 ` nguyenb
[not found] ` <0101017475a11d00-6def34a7-db5d-472c-9dcc-215a80510402-000000@us-west-2.amazonses.com>
2020-09-10 10:02 ` Avri Altman
2020-09-14 16:34 ` nguyenb [this message]
2020-09-15 2:54 ` Bjorn Andersson
2020-09-15 8:49 ` nguyenb
2020-09-15 13:37 ` Bjorn Andersson
2020-09-17 0:53 ` nguyenb
2020-09-17 2:29 ` Bjorn Andersson
2020-09-29 2:35 ` nguyenb
2020-10-26 20:48 ` nguyenb
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