Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753645Ab2EBHyS (ORCPT ); Wed, 2 May 2012 03:54:18 -0400 Received: from cantor2.suse.de ([195.135.220.15]:59750 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751913Ab2EBHyR (ORCPT ); Wed, 2 May 2012 03:54:17 -0400 From: Jean Delvare Organization: Suse Linux To: Luca Tettamanti Subject: Re: Linux 3.4-rc4 Date: Wed, 2 May 2012 09:54:13 +0200 User-Agent: KMail/1.12.4 (Linux/2.6.32.54-0.3-pae; KDE/4.3.5; i686; ; ) Cc: Maarten Maathuis , Dmitry Torokhov , Nick Bowler , Martin Peres , Linus Torvalds , Linux Kernel Mailing List , dri-devel@lists.freedesktop.org, Ben Skeggs References: <20120422164023.GA32342@elliptictech.com> In-Reply-To: MIME-Version: 1.0 Content-Type: Text/Plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <201205020954.13273.jdelvare@suse.de> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 7709 Lines: 172 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 wrote: > > On Mon, Apr 30, 2012 at 12:37 AM, Dmitry Torokhov > > > > 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 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 > 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 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 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. 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. -- Jean Delvare Suse L3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/