[RFC] NAND: Optimize NAND_ECC_HW_OOB_FIRST read

[Boris Brezillon]

On Mon, 30 Oct 2017 18:17:50 +0530
PrasannaKumar Muralidharan <prasannatsmkumar at gmail.com> wrote:

> Hi Boris,
> 
> On 30 October 2017 at 14:04, Boris Brezillon
> <boris.brezillon at free-electrons.com> wrote:
> > Hi PrasannaKumar,
> >
> > On Sat, 28 Oct 2017 13:13:51 +0530
> > PrasannaKumar Muralidharan <prasannatsmkumar at gmail.com> wrote:
> >  
> >> From: Lars-Peter Clausen <lars at metafoo.de>
> >>
> >> Avoid sending unnecessary READ commands to the chip.
> >>
> >> Signed-off-by: Lars-Peter Clausen <lars at metafoo.de>
> >> Signed-off-by: PrasannaKumar Muralidharan <prasannatsmkumar at gmail.com>
> >> ---
> >> This patch is taken from git://projects.qi-hardware.com/qi-kernel.git
> >> branch jz-3.16. From [1] and [2] it can be seen that the patch author
> >> thinks this can be sent upstream but it never happened so far. This
> >> patch is used in OpenWRT as seen from [3].  
> >
> > Sounds reasonable, but it's likely to conflict with something I'd like
> > to queue for 4.16 [1]. I'll rebase this patch on nand/next once the  
> > ->exec_op() series is merged. Don't hesitate to ping me if I forget.  
> >
> > Regards,
> >
> > Boris
> >
> > [1]http://patchwork.ozlabs.org/project/linux-mtd/list/?series=8923  
> 
> Okay. I will remind you if required.
> 
> There is another patch used in OpenWRT at [1]. Do you mind to have a
> look at it and take that if it is useful? I don't see a point in me
> sending it as a RFC as I am not contributing anything to it other than
> noticing its existence.

Yep, it makes sense to have that one applied too, but this is pretty
much the same problem: it will conflict with the ->exec_op() rework.

Can you please send it to the ML so I can track it in patchwork and
respin it when ->exec_op() is out. I'll also need someone owning a HW
using NAND_ECC_HW_OOB_FIRST to test the changes. Do you have such HW?

> 
> 1. https://git.lede-project.org/?p=source.git;a=blob;f=target/linux/xburst/patches-3.18/003-NAND-Add-support-for-subpage-reads-for-NAND_ECC_HW_O.patch;h=974eb7a5db9a09347fa6137461f030575f9a4328;hb=c03d4317a6bc891cb4a5e89cbdd77f37c23aff86
> 
> Thanks,
> PrasannaKumar