[REVERT] drm/radeon: consolidate vga and dvi get_modes functions (v2)

[REVERT] drm/radeon: consolidate vga and dvi get_modes functions (v2)

[Tony Vroon]

Please consider reverting commit 3e22920fbd0005927bc41f71daeb056a0f4def82 by title of:
drm/radeon: consolidate vga and dvi get_modes functions (v2)

I have bisected this as the culprit for my PowerMac 7,3 crashing back into OpenFirmware 
very early at boot with an invalid memory access. The diagnostic data printed is:
%SSR0: 0000000.00c00000
%SSR1: 1000000.0083030

Regards,
Tony V.

Re: [REVERT] drm/radeon: consolidate vga and dvi get_modes functions (v2)

[Benjamin Herrenschmidt]

On Sat, 2014-08-30 at 18:37 +0100, Tony Vroon wrote:
> Please consider reverting commit 3e22920fbd0005927bc41f71daeb056a0f4def82 by title of:
> drm/radeon: consolidate vga and dvi get_modes functions (v2)
> 
> I have bisected this as the culprit for my PowerMac 7,3 crashing back into OpenFirmware 
> very early at boot with an invalid memory access. The diagnostic data printed is:
> %SSR0: 0000000.00c00000
> %SSR1: 1000000.0083030

This is weird. The above means it crashed very early, such as in
prom_init. I fail to see how the above commit can possibly relate
to that in any way...

Have you verified that reverting it actually helps ?

Cheers,
Ben.

Re: [REVERT] drm/radeon: consolidate vga and dvi get_modes functions (v2)

[Tony Vroon]

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On 30/08/14 22:56, Benjamin Herrenschmidt wrote:
> This is weird. The above means it crashed very early, such as in
> prom_init. I fail to see how the above commit can possibly relate
> to that in any way...

I was dubious as well, but this git bisection process is held up as the
one and only truth in kernel troubleshooting and I followed it to the
letter.

> Have you verified that reverting it actually helps ?

I just tried it on a clean tree and indeed, it did not help as you expected.

So, Alex, sorry to waste your time.

Ben, other ideas?

Regards,
-- 
Tony Vroon
Server systems manager
London Internet Exchange Ltd, Trinity Court, Trinity Street,
Peterborough, PE1 1DA
Registered in England number 3137929
E-Mail: tony@linx.net


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Re: [REVERT] drm/radeon: consolidate vga and dvi get_modes functions (v2)

[Benjamin Herrenschmidt]

On Sat, 2014-08-30 at 23:38 +0100, Tony Vroon wrote:
> On 30/08/14 22:56, Benjamin Herrenschmidt wrote:
> > This is weird. The above means it crashed very early, such as in
> > prom_init. I fail to see how the above commit can possibly relate
> > to that in any way...
> 
> I was dubious as well, but this git bisection process is held up as the
> one and only truth in kernel troubleshooting and I followed it to the
> letter.
> 
> > Have you verified that reverting it actually helps ?
> 
> I just tried it on a clean tree and indeed, it did not help as you expected.
> 
> So, Alex, sorry to waste your time.
> 
> Ben, other ideas?

I'll have to experiment on my own G5's next week

Cheers,
Ben.