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@gmail.com wrote:
On Mon, Apr 30, 2012 at 12:37 AM, Dmitry Torokhov
dmitry.torokhov@gmail.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@elliptictech.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@suse.de Date: Sat Jan 28 11:07:09 2012 +0100
drm/kms: Make i2c buses fasterdoubled 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@redhat.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@redhat.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.