Re: [PATCH] scsi: associate bio write hint with WRITE CDB

From: Martin K. Petersen
Date: Fri Jan 04 2019 - 01:12:11 EST

Hi Randall,

> I am working on Android phone.

> The idea is to enable write hint for Turbo write UFS feature. Turbo
> write feature in UFS 3.x is under discussion in JEDEC JC-64. This
> patch is the under-lying framework for supporting this feature.

OK, but we can't blindly go setting GROUP NUMBER to a non-zero value.
That'll break a massive amount of devices which will fail READ/WRITE
commands with INVALID FIELD IN CDB.

So aside from requiring the device to report GROUP_SUP=1, we'll need
some sort of indication that this device supports the UFS Turbo Write
feature. If you are engaged with JEDEC on this, please tell them we'll
need a VPD page, a mode page, or something similar to use as trigger to
entertain enabling this feature.

Martin K. Petersen Oracle Linux Engineering