> -----Original Message----- > From: Timur Kristóf [mailto:timur.kristof@xxxxxxxxx] > Sent: Thursday, May 31, 2018 12:14 PM > To: Pali Rohár > Cc: Andy Shevchenko; Limonciello, Mario; Platform Driver; Timur Kristóf; Matthew > Garrett; Darren Hart; Andy Shevchenko > Subject: Re: [PATCH] Fix AC keyboard backlight timeout on Dell XPS 13 9370. > > On Thu, 2018-05-31 at 14:50 +0200, Pali Rohár wrote: > > On Thursday 31 May 2018 14:35:45 Timur Kristóf wrote: > > > On Thu, 2018-05-31 at 14:22 +0200, Pali Rohár wrote: > > > > On Thursday 31 May 2018 15:05:39 Andy Shevchenko wrote: > > > > > +Cc: Mario > > > > > > > > > > On Thu, May 24, 2018 at 9:07 PM, Timur Kristóf <timur.kristof@g > > > > > mail > > > > > .com> wrote: > > > > > > From: Timur Kristóf <venemo@xxxxxxxxxxxxxxxxx> > > > > > > > > > > > > The 9370 doesn't expose the necessary KBD_LED_AC_TOKEN in the > > > > > > BIOS, so the driver thinks it cannot adjust the AC keyboard > > > > > > backlight timeout. This patch adds a quirk to fix this until > > > > > > Dell adds the missing token to their BIOS. > > > > > > > > > > > > For further discussion, see: > > > > > > https://github.com/dell/libsmbios/issues/48 > > > > > > > > > > > > > > > > The change per se looks good to me, though I would hear back > > > > > from > > > > > Pali > > > > > and / or Mario on the subject. > > > > > Their formal Ack would be enough. > > > > > > > > I do not know what is happening here. So Mario should comment if > > > > this > > > > is > > > > really a BIOS bug (and we need to workaround it by DMI > > > > whitelisting) > > > > or > > > > kernel has incorrect implementation (and different fix is > > > > needed). > > > > > > Discussed with Mario here: > > > https://github.com/dell/libsmbios/issues/48 > > > > > > The conclusion is that this is a BIOS bug. The machine is capable > > > of > > > changing the AC keyboard backlight timeout setting, it is just > > > missing > > > the token which indicates the capability. > > > > Can you try to report this problem to Dell support (if possible)? > > Really > > if Dell is interested in good Linux support (which looks like yes), > > then > > Dell should know that has a bug in BIOS/firmware which is causing > > problems on Linux. > > > > For me it sounds stupid to adding hacks into kernel which just due to > > firmware bugs about which vendor does not know. > > > > As a short term fix for one laptop it is OK, but not if Dell starts > > producing e.g. new generation of all laptops with same bug. Long term > > fix is for sure in BIOS/firmware. > > > > I already wrote this to above github issue. > > > > Thank you Pali. I agree with your point. Let's hope they will fix it in > the 9380. In the meantime I think it doesn't hurt to add the patch for > people who use the 9370 now. I of course can't make any guarantees in what bugs are introduced in new generations of hardware, but I would say that it's at least understood why this behavior occurs on the 9370. I hope it should be fixed in a future firmware version but I also can not guarantee that. I think that v2 of this patch looks fine, but I would like to ask Timur that if a firmware is released that fixes this behavior please amend with a follow up patch that restricts the quirk only to the applicable firmware (or drop the quirk).
