RE: [EXT] [PATCH v1 1/3] scsi: ufs: fix empty check of error history

[Bean Huo (beanhuo)]

> Subject: RE: [EXT] [PATCH v1 1/3] scsi: ufs: fix empty check of error history
> 
> Hi Bean,
> 
> On Mon, 2020-01-13 at 09:28 +0000, Bean Huo (beanhuo) wrote:
> > Hi, Stanley
> >
> > >
> > > Currently checking if an error history element is empty or not is by
> > > its "value". In most cases, value is error code.
> > >
> > > However this checking is not correct because some errors or events
> > > do not specify any values in error history so values remain as 0,
> > > and this will lead to incorrect empty checking.
> > >
> > Do you think this is a bug of UFS host controller? According to the
> > UFS host Spec, If there had error detected in each layer, at least
> > bit31 in its error code register Should be set to 1.
> >
> > Why there was an error happening, but host didn't set this bit31?
> >
> 
> Thanks so much for review.
> 
> Yes, the case bit[31] set is true for UIC errors.
> 
> However the users of UFS error history, i.e., users of ufshcd_update_reg_hlist(),
> are not only UIC errors. Some other essential events will update history too, for
> example, device reset events and abort events.
> 
> Take "device reset events" as example: parameter "val" may be 0 while invoking
> ufshcd_update_reg_hlist(). If this happens, the device reset event will not be
> printed out because its err_hist->reg[p] is 0 according to the original logic in
> ufshcd_print_err_hist().
> 
> Feel free to correct above description if it is wrong.
> 
> Thanks,
> Stanley

Hi, Stanley
Thanks, now clear, it is not controller negative act issue.

Reviewed-by: Bean Huo <beanhuo@xxxxxxxxxx>