Bug#944350: RE: Bug#944350: RE: [External] Bug#944350: systemd: screen remains off after waking up from suspend

[Mark Pearson <mpearson@lenovo.com>]

Hi,

The BIOS fix was actually just an initial workaround - the proper fix is the kernel patch (https://patchwork.freedesktop.org/patch/338599/?series=68817&rev=4 )which went into 5.4-rc8 and has also been backported into Debian sid at the end of last year

To add some context/detail in case it helps or is of interest: We found the issue and worked with Intel - in summary the wrong clock was used on resume and it meant, for OLED panels, not enough time was allowed for initialization/training to complete and this sometimes leads to a black screen (ssh etc still works). The BIOS fix was to increase the timeout (from the spec version of 200ms to 210ms I believe) but it's just a workaround. We released it as we had some customers who needed the fix quickly and we were worried it would take a long time for the patch to upstream and then to get into the distros. Releasing a new BIOS isn't a fast process and as it turned out the kernel patch went through really fast (doesn't always happen 😊) so we probably could have skipped the BIOS workaround, but the tweak is minor and safe so it's good to have it available for those needing to use an older kernel. 

Summary: If you're running a newer kernel than 5.4-rc8 and don't care about the enhancements in the update you don't need to update the BIOS for the timing fix. 

Let me know if any questions.
Mark

> -----Original Message-----
> From: Jiri Kanicky <j@ganomi.com>
> Sent: Sunday, January 26, 2020 11:48 PM
> To: 944350@bugs.debian.org
> Subject: Bug#944350: RE: Bug#944350: RE: [External] Bug#944350: systemd:
> screen remains off after waking up from suspend
> 
> FYI Lenovo also pushed a fix into a BIOS.
> 
> CHANGES IN THIS RELEASE
>   Version 1.28
> 
> [Important updates]
>   Nothing
> 
> [New functions or enhancements]
> - Supported BIOS password authentication before entering into MEBx.
> - Updated Regulatory Information.
> 
> [Problem fixes]
> - Fixed an issue where OLED panel might not trun on after resuming from
> sleep on Linux.
> 
> https://download.lenovo.com/pccbbs/mobiles/n2oul07w.txt
> 
> 
> 
> 
> 
> Regards, Jiri
> 
> 
> 
> 
> 
> On Fri, 6 Dec 2019 18:47:05 +0000 Mark Pearson <mpearson@lenovo.com>
> <mailto:mpearson@lenovo.com>  wrote:
> 
> > Hi Jiri,
> >
> > I'm pretty sure it's not in 5.3.0-2. Are you sure? I can look again but I
> recently did put in a merge request to get it pulled into sid:
> https://salsa.debian.org/kernel-team/linux/merge_requests/188
> >
> > Not sure if/when it will be accepted (it's only my 2nd attempt at doing this)
> but hopefully someone looks at it and thinks it's useful)
> >
> > Mark
> >
> > > -----Original Message-----
> > > From: Jiri Kanicky <j@ganomi.com> <mailto:j@ganomi.com>
> > > Sent: Saturday, November 30, 2019 6:56 AM
> > > To: 944350@bugs.debian.org <mailto:944350@bugs.debian.org>
> > > Subject: Bug#944350: RE: [External] Bug#944350: systemd: screen
> remains
> > > off after waking up from suspend
> > >
> > > Hi.
> > >
> > > It seems that Debian 5.3.0-2-amd64 includes the code in the patch
> > > already and I still have the issue.
> > >
> > > Jiri
> > >
> > > On Mon, 25 Nov 2019 16:45:55 +0000 Mark Pearson
> > > <mpearson@lenovo.com> <mailto:mpearson@lenovo.com>  wrote:
> > >
> > > > Hi,
> > > >
> > > > I don't know if this is helpful but I recently debugged a similar
> > > issue on the Lenovo P1Gen2. There the problem is only with the
> > > integrated graphics and an OLED screen - we tracked it down to an issue
> > > in the i915 driver where it wasn't giving enough time for eDP link
> > > training. It turned out this was due to the driver using the wrong
> > > clocks after a suspend and resume .
> > > >
> > > > Intel recently up-streamed a fix (commit 2f216a85 - it went into
> > > 5.4-rc8)
> > > >
> > > > I'm working on doing a patch that I'm hoping to get into Debian to
> > > backport - just not done yet :) The patch is pretty small (I've attached
> > > it) so you might want to give it a go and see if it helps.
> > > >
> > > > Note - we did also test X1 extreme with OLED panel and didn't see a
> > > problem there....but it's a really subtle timing issue so some units
> > > might be more susceptible than others. Maybe worth a go?
> > > >
> > > > If it does make a difference let me know.
> > > > Mark
> > > >
> >
>