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Message-ID: <1335958306.1898.7.camel@nisroch> Date: Wed, 02 May 2012 21:31:46 +1000 From: Ben Skeggs <bskeggs@...hat.com> To: Jean Delvare <jdelvare@...e.de> Cc: Luca Tettamanti <kronos.it@...il.com>, Maarten Maathuis <madman2003@...il.com>, Dmitry Torokhov <dmitry.torokhov@...il.com>, Nick Bowler <nbowler@...iptictech.com>, Martin Peres <martin.peres@...ri.fr>, Linus Torvalds <torvalds@...ux-foundation.org>, Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, dri-devel@...ts.freedesktop.org Subject: Re: Linux 3.4-rc4 On Wed, 2012-05-02 at 09:54 +0200, Jean Delvare wrote: > Hi Luca, Maarten, > > On Monday 30 April 2012 01:01:30 pm Luca Tettamanti wrote: > > On Mon, Apr 30, 2012 at 11:07 AM, Maarten Maathuis <madman2003@...il.com> wrote: > > > On Mon, Apr 30, 2012 at 12:37 AM, Dmitry Torokhov > > > > > > <dmitry.torokhov@...il.com> wrote: > > >> On Sat, Apr 28, 2012 at 11:33:50AM -0400, Nick Bowler wrote: > > >>> On 2012-04-28 02:19 -0400, Alex Deucher wrote: > > >>> > On Fri, Apr 27, 2012 at 8:39 PM, Nick Bowler <nbowler@...iptictech.com> wrote: > > >>> > > Unfortunately, that's not the end of my VGA-related > > >>> > > regressions. :( > > >>> > > > > >>> > > While tracking down the black screen issue, I've been having > > >>> > > the monitor directly connected to the video card the whole > > >>> > > time, but now when I'm connected through my KVM switch (an > > >>> > > IOGear GCS1804), it appears that something's going wrong with > > >>> > > reading the EDID, because the available modes are all screwed > > >>> > > up (both console and X decide they want to drive the display > > >>> > > at 1024x768). Here's the output of xrandr on 3.2.15: > > >>> > > > > >>> > > % xrandr > > >>> > > Screen 1: minimum 320 x 200, current 1600 x 1200, maximum > > >>> > > 4096 x 4096 VGA-1 connected 1600x1200+0+0 (normal left > > >>> > > inverted right x axis y axis) 352mm x 264mm > > >>> > > 1600x1200 75.0*+ 70.0 65.0 60.0 > > >>> > > 1280x1024 85.0 + 75.0 60.0 > > >>> > > 1920x1440 60.0 > > >>> > > 1856x1392 60.0 > > >>> > > 1792x1344 60.0 > > >>> > > 1920x1200 74.9 59.9 > > >>> > > 1680x1050 84.9 74.9 60.0 > > >>> > > 1400x1050 85.0 74.9 60.0 > > >>> > > 1440x900 84.8 75.0 59.9 > > >>> > > 1280x960 85.0 60.0 > > >>> > > 1360x768 60.0 > > >>> > > 1280x800 84.9 74.9 59.8 > > >>> > > 1152x864 75.0 > > >>> > > 1280x768 84.8 74.9 59.9 > > >>> > > 1024x768 85.0 75.1 75.0 70.1 60.0 43.5 43.5 > > >>> > > 832x624 74.6 > > >>> > > 800x600 85.1 72.2 75.0 60.3 56.2 > > >>> > > 848x480 60.0 > > >>> > > 640x480 85.0 75.0 72.8 72.8 66.7 60.0 59.9 > > >>> > > 720x400 85.0 87.8 70.1 > > >>> > > 640x400 85.1 > > >>> > > 640x350 85.1 > > >>> > > 320x200 165.1 > > >>> > > > > >>> > > And on 3.4-rc4+ (with your patch cherry-picked): > > >>> > > > > >>> > > % xrandr > > >>> > > Screen 1: minimum 320 x 200, current 1024 x 768, maximum > > >>> > > 4096 x 4096 VGA-1 connected 1024x768+0+0 (normal left > > >>> > > inverted right x axis y axis) 0mm x 0mm > > >>> > > 1024x768 60.0* > > >>> > > 800x600 60.3 56.2 > > >>> > > 848x480 60.0 > > >>> > > 640x480 59.9 > > >>> > > 320x200 165.1 > > >>> > > > > >>> > > Running xrandr on 3.4-rc4+ also causes the screen to go black > > >>> > > for a second when it does not on 3.2.15. It also causes > > >>> > > several messages of the form > > >>> > > > > >>> > > [drm] nouveau 0000:01:00.0: Load detected on output B > > >>> > > > > >>> > > to be logged. Also, looking at > > >>> > > /sys/class/drm/card0-VGA-1/edid I see that it is empty on > > >>> > > 3.4-rc4+ and it is correct on 3.2.15. Things seem to work OK > > >>> > > when the KVM is not involved. > > >>> > > > >>> > Were you ever able to fetch a EDID with the KVM involved? KVMs > > >>> > are notorious for not connecting the ddc pins. > > >>> > > >>> Yes, it works on 3.2.15 as described above. > > >> > > >> I have the same (or similar) KVM (not in the office at the moment) > > >> and I can confirm that with newer kernels EDID fecthing in flaky. > > >> It's 50/50 if EDED retrieval succeeds or if it fails with: > > >> > > >> Apr 26 13:06:57 dtor-d630 kernel: [13464.936336] > > >> [drm:drm_edid_block_valid] *ERROR* EDID checksum is invalid, > > >> remainder is 208 Apr 26 13:06:57 dtor-d630 kernel: [13464.955317] > > >> [drm:drm_edid_block_valid] *ERROR* EDID checksum is invalid, > > >> remainder is 208 Apr 26 13:06:57 dtor-d630 kernel: [13464.973879] > > >> [drm:drm_edid_block_valid] *ERROR* EDID checksum is invalid, > > >> remainder is 208 Apr 27 09:13:03 dtor-d630 kernel: [44602.087659] > > >> [drm:drm_edid_block_valid] *ERROR* EDID checksum is invalid, > > >> remainder is 208 Apr 27 09:13:03 dtor-d630 kernel: [44602.107147] > > >> [drm:drm_edid_block_valid] *ERROR* EDID checksum is invalid, > > >> remainder is 208 Apr 27 09:13:03 dtor-d630 kernel: [44602.126908] > > >> [drm:drm_edid_block_valid] *ERROR* EDID checksum is invalid, > > >> remainder is 208 Apr 27 09:13:03 dtor-d630 kernel: [44602.146277] > > >> [drm:drm_edid_block_valid] *ERROR* EDID checksum is invalid, > > >> remainder is 208 Apr 27 09:13:03 dtor-d630 kernel: [44602.297659] > > >> [drm:drm_edid_block_valid] *ERROR* EDID checksum is invalid, > > >> remainder is 208 Apr 27 09:13:03 dtor-d630 kernel: [44602.317063] > > >> [drm:drm_edid_block_valid] *ERROR* EDID checksum is invalid, > > >> remainder is 208 > > >> > > >> Earlier kernels were able to retrieve EDEDs reliably. > > >> > > >> This is with: > > >> > > >> [ 1.678392] [drm] nouveau 0000:01:00.0: Detected an NV50 > > >> generation card (0x086b00a2) > > > > > > Just a crazy thought, but didn't we change some timings related to > > > EDID retrieval? To make it faster. > > > > Hum, this commit: > > > > commit 1849ecb22fb3b5d57b65e7369a3957adf9f26f39 > > Author: Jean Delvare <jdelvare@...e.de> > > Date: Sat Jan 28 11:07:09 2012 +0100 > > > > drm/kms: Make i2c buses faster > > > > doubled the data rate but only for radeon and intel drivers. nouveau > > doesn't use the standard i2c-algo-bit helpers (BTW: the > > cond_resched() has been removed), and AFAICS it's using 1us delay; > > the other drivers are using 10us, 1us seems a bit too low... > > As I read the code, it is actually using a 6 us delay. This is fast > but reasonable, especially when the code handles clock stretching > > Ben Skeggs (Cc'd) rewrote the I2C handling code in the nouveau > driver completely in kernel 3.3: > > commit f553b79c03f0dbd52f6f03abe8233a2bef8cbd0d > Author: Ben Skeggs <bskeggs@...hat.com> > Date: Wed Dec 21 18:09:12 2011 +1000 > > drm/nouveau/i2c: handle bit-banging ourselves > > i2c-algo-bit doesn't actually work very well on one card I have access to > (NVS 300), random single-bit errors occur most of the time - what we're > doing now is closer to what xf86i2c.c does. > > The original plan was to figure out why i2c-algo-bit fails on the NVS 300, > and fix it. However, while investigating I discovered i2c-algo-bit calls > cond_resched(), which makes it a bad idea for us to be using as we execute > VBIOS scripts from a tasklet, and there may very well be i2c transfers as > a result. > > So, since I already wrote this code in userspace to track down the NVS 300 > bug, and it's not really much code - lets use it. > > Signed-off-by: Ben Skeggs <bskeggs@...hat.com> > > So if the regression happened between 3.2.15 and 3.4-rc4, that would be > a good candidate. > > BTW, Ben, there were two interesting fixes to i2c-algo-bit meanwhile, > you may want to try using it again. Hey Jean, Thanks! I did notice this, and your email, a while back. I just haven't yet had the time to see how the NVS300 goes now. I do definitely plan on taking a peek however. Ben. > > Maarten, another commit you may want to try reverting is > 9292f37e1f5c79400254dca46f83313488093825 . If none of the above works, > it would be great if you could test your KVM with another graphics > adapter, so that we know if we are looking for a nouveau-specific bug > or rather an issue in the common i2c or edid code. Otherwise a plain > bisection is probably the way to go. > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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