Messages in this thread | | | Date | Mon, 14 Sep 2020 09:34:43 -0700 | From | nguyenb@codeauro ... | Subject | Re: [PATCH v1 1/1] scsi: ufshcd: Properly set the device Icc Level |
| |
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
| |