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

[Joakim Tjernlund]

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.
> > > 
> > > 
> > > Hi Joakim,
> > > 
> > > Joakim Tjernlund <Joakim.Tjernlund at infinera.com> wrote on Fri, 30 Oct
> > > 2020 18:39:35 +0000:
> > > 
> > > > On Fri, 2020-10-30 at 18:47 +0100, Miquel Raynal wrote:
> > > > > 
> > > > > Hi Joakim,
> > > > 
> > > > Hi Miquel
> > > > 
> > > > > 
> > > > > Please Cc the MTD maintainers, not only the list (get_maintainers.pl).
> > > > 
> > > > I figure all maintainers are on the list ?
> > > 
> > > I personally don't look at the list very often. I expect patches to be
> > > directed to me (in the current case, Vignesh) when I am concerned.
> > 
> > Added Vignesh
> > 
> 
> As Miquel suggested, I look at patches on mailing list at a lower
> priority than patches that are CC'd to me.
> 
> 
> > > 
> > > > 
> > > > > 
> > > > > Joakim Tjernlund <joakim.tjernlund at infinera.com> wrote on Thu, 22 Oct
> > > > > 2020 17:45:06 +0200:
> > > > > 
> > > > > > Commit "mtd: cfi_cmdset_0002: Add support for polling status register"
> > > > > > added support for polling the status rather than using DQ polling.
> > > > > > However, status register is used only when DQ polling is missing.
> > > > > > Lets use status register when available as it is superior to DQ polling.
> > > > > > 
> > > > > 
> > > > > I will let vignesh comment about the content (looks fine by me) but you will
> > > > > need a Fixes tag here.
> > > > 
> > > > This is not a Fixes situation, no bug just a hw enabling thing.
> > > > Also, I would like to see the Status patches be backported to 4.19 as well.
> > > 
> > > Backporting features is IMHO not relevant. I guess stable kernel only
> > > take fixes...
> > 
> > This is not a feature really and the 5.4 stable did get them, I ask 4.19 get them too.
> > 
> 
> 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



 Jocke