[PATCH] mtd: cfi_cmdset_0002: Use status register where possible

[Joakim Tjernlund]

On Thu, 2020-11-05 at 21:34 +0530, Vignesh Raghavendra wrote:
> 
> On 11/4/20 3:23 PM, Joakim Tjernlund wrote:
> > On Wed, 2020-11-04 at 11:12 +0530, Vignesh Raghavendra wrote:
> > > Hi Joakim
> > > 
> > > On 10/31/20 4:56 PM, Joakim Tjernlund wrote:
> > > > On Fri, 2020-10-30 at 19:52 +0100, Miquel Raynal wrote:
> > > > > CAUTION: This email originated from outside of the organization. Do not click links or open attachments unless you recognize the sender and know the content is safe.
> > > > > 
> > > > > 
> [...]
> > > commit 4844ef80305d ("mtd: cfi_cmdset_0002: Add support for polling
> > > status register") was added in 5.3 and therefore is part of 5.4. But
> > > note that this is a "new feature" and therefore won't be backported to
> > > kernels older than 5.3.
> > 
> > Oh, my memory is off then, sorry.
> > 
> > > Similarly, this patch (when accepted) is not a candidate for stable
> > > kernel backports because the intention of enabling polling status
> > > register for Write Completion is to enable flashes that "don't" support
> > > DQ polling at all (mainly HyperFlash).
> > > Enabling this for all flashes that support the feature is not a bug fix
> > > IMO. Also, there isn't enough testing to prove that feature works for
> > > all CFI NOR flashes on all platforms and therefore would be risky to be
> > > backported to stable kernels.
> > 
> > This is 2 things,
> >  1. making it possible to use Hyper flash (HW enablement)
> >  2. improving the flash driver to function more precise(getting an accurate error rather than a TMO) for most AMD flashes.
> > 
> > 1. happens on a regular basis in stable.
> > 2. can be discussed for stable but should at least go into master now that status has been in there for a while
> > 
> 
> Yes, but my objection is that there has not been enough testing to prove
> that its safe to backport to stable kernels and there is nothing that's
> broken in older kernels which this patch fixes.

Semi broken though. I stumbled upon some erase failures that just resulted in a super long TMO error
rather than report a failure directly(the page was locked).

There I no way to improve upon error handling without your status updates and this is
the main reason I want your patches backported to 4.19 as well.

My patch can be dropped for stable, giving it time to mature in master though.

 Jocke