Re: [PATCH 1/1] Fix PCIe LER when GRUB2 accesses non-enabled MMIO data from VGA

[Hans de Goede]

Hi,

On 29-03-18 16:27, Mike Travis wrote:
> On 3/29/2018 2:36 AM, Daniel Kiper wrote:
> > On Thu, Mar 29, 2018 at 05:29:01PM +0800, Michael Chang wrote:
> > > On Thu, Mar 29, 2018 at 11:02:51AM +0200, Daniel Kiper wrote:
> > > > On Wed, Mar 28, 2018 at 11:42:18AM -0500, address@hidden wrote:
> > > > > A GPU inserted into a PCIe I/O slot disappears during system startup.
> > > > > The problem centers around GRUB and a specific VGA init function in
> > > > > efi_uga.c.  This causes an LER (link error recorvery) because the MMIO
> > > > > memory has not been enabled before attempting access.
> > > > >
> > > > > The fix is to add the same coding used in other VGA drivers, specifically
> > > > > to add a check to insure that it is indeed a VGA controller.  And then
> > > > > enable the MMIO address space with the specific bits.
> > > > >
> > > > > Signed-off-by: Mike Travis <address@hidden>
> > > > > Reviewed-by: Michael Chang <address@hidden>
> > > > > Reviewed-by: Daniel Kiper <address@hidden>
> > > >
> > > > Well, please do not add somebody RB tag if he/she did not explicitly
> > > > asked you to do that. And even in that case I was not able to look at
> > > > this patch in advance. So, my RB should not be here. Additionally, in
> > > > this situation I would like to ask if Michael approved his RB?
> > >
> > > We did have discussion about the patch before it was submitted upstream but I
> > > did not ask for RB as well.
> > >
> > > > Anyway, patch LGTM except one nitpick. I will apply the patch, in a week or
> > > > so, with Michael's RB if I get confirmation that he approved it earlier.
> > >
> > > As I did not ask for it, it has to be removed.
> >
> > OK, I will commit this patch without your RB.
> >
> > Daniel
>
> Sorry, I was not aware of this custom.  I thought that if someone reviewed the code then 
> that was an indication that it should be noted. I am aware of the more restrictive 
> Acked-by which is normally sent by the "acker" to the submitter.  I will be 
> more mindful of this in the future.  (This is my first posting to any of the GNU mail 
> lists).

Reviewed-by actually is stronger then Acked-by at least that is
what I believe, I've always interpreted these 2 as:

Acked-by: foo:     Foo took a quick glance at the proposed changes and thinks 
this is a sensible change
Reviewed-by: foo:  Foo did a detailed review of the code and did not find any 
issues

Regards,

Hans