Re: [PATCH AUTOSEL 4.9 08/10] Revert "usb: storage: Add quirk for Samsung Fit flash"

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Mon, Oct 17, 2022 at 02:46:32PM +0200, Pavel Machek wrote:
> Hi!
> 
> > From: sunghwan jung <onenowy@gmail.com>
> > 
> > [ Upstream commit ad5dbfc123e6ffbbde194e2a4603323e09f741ee ]
> > 
> > This reverts commit 86d92f5465958752481269348d474414dccb1552,
> > which fix the timeout issue for "Samsung Fit Flash".
> > 
> > But the commit affects not only "Samsung Fit Flash" but also other usb
> > storages that use the same controller and causes severe performance
> > regression.
> > 
> >  # hdparm -t /dev/sda (without the quirk)
> >  Timing buffered disk reads: 622 MB in  3.01 seconds = 206.66 MB/sec
> > 
> >  # hdparm -t /dev/sda (with the quirk)
> >  Timing buffered disk reads: 220 MB in  3.00 seconds =  73.32 MB/sec
> > 
> > The commit author mentioned that "Issue was reproduced after device has
> > bad block", so this quirk should be applied when we have the timeout
> > issue with a device that has bad blocks.
> > 
> > We revert the commit so that we apply this quirk by adding kernel
> > paramters using a bootloader or other ways when we really need it,
> > without the performance regression with devices that don't have the
> > issue.
> 
> Re-introducing timeouts for users in middle of stable series... may
> not be nice. Is there better fix in a follow up to this that was not
> backported?

No.

thanks,

greg k-h