Tejun Heo wrote:
So, I don't think the problem exists for SATA in the first place. At least there hasn't been any report of it and doing SETXFER by polling can handle all the existing cases. We can and probably should deal with such SATA devices when and if they come up. How are we gonna verify the controller doesn't crap itself and ahci TF register monitoring HSM can work around the weirdo when we don't have any such device? Even if we determine that we need to do HSM over intelligent SATA controller now, I think we still need to push polling SETXFER first to take care of the existing cases.
Doing SETXFER by polling only handles the cases where the driver actually honors ATA_TFLAG_POLLING, which is /not/ always the case.
If the new policy ensures that it continues to be OK to /not/ honor ATA_TFLAG_POLLING -- thus limiting SETXFER polling assumptions to older hardware -- that's fine, and it merely needs to be documented.
But let us not make the assumption that this bandaid fixes all cases, because the bandaid is not applied in all cases.
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