Re: [BUG] mtd: cfi_cmdset_0002: write regression since v4.17-rc1

[Tokunori Ikegami]

Hi Ahmad-san,

On 2022/02/15 1:22, Ahmad Fatoum wrote:
> Hello Tokunori-san,
>
> On 13.02.22 17:47, Tokunori Ikegami wrote:
> > Hi Ahmad-san,
> >
> > Thanks for your confirmations. Sorry for late to reply.
> No worries. I appreciate you taking the time.
>
> > Could you please try the patch attached to disable the chip_good() change as before?
> > I think this should work for S29GL964N since the chip_ready() is used and works as mentioned.
> yes, this resolves my issue:
> Tested-by: Ahmad Fatoum <a.fatoum@xxxxxxxxxxxxxx>
Thanks for your testing. I have just sent the patch to review.
> > > > > Doesn't seem to be a buffered write issue here though as the writes
> > > > > did work fine before dfeae1073583. Any other ideas?
> > > > At first I thought the issue is possible to be resolved by using the word write instead of the buffered writes.
> > > > Now I am thinking to disable the changes dfeae1073583 partially with any condition if possible.
> > > What seems to work for me is checking if chip_good or chip_ready
> > > and map_word is equal to 0xFF. I can't justify why this is ok though.
> > > (Worst case bus is floating at this point of time and Hi-Z is read
> > > as 0xff on CPU data lines...)
> > Sorry I am not sure about this.
> > I thought the chip_ready() itself is correct as implemented as the data sheet in the past.
> > But it did not work correctly so changed to use chip_good() instead as it is also correct.
> What exactly in the datasheet makes you believe chip_good is not appropriate?
I just mentioned about the actual issue behaviors as not worked 
chip_good() on S29GL964N and not worked chip_ready() on 
MX29GL512FHT2I-11G before etc.
Anyway let me recheck the data sheet details as just checked it again 
quickly but needed more investigation to understand.

Regards,
Ikegami

> Cheers,
> Ahmad