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* fb_ddc: fix DDC lines quirkJean Delvare2007-11-291-4/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The code in fb_ddc_read() is said to be based on the implementation of the radeon driver: http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=fc5891c8a3ba284f13994d7bc1f1bfa8283982de However, comparing the old radeon driver code with the new fb_ddc code reveals some differences. Most notably, the I2C bus lines are held at the end of the function, while the original code was releasing them (as the comment above correctly says.) There are a few other differences, which appear to be responsible for read failures on my system. While tracing low-level I2C code in i2c-algo-bit, I noticed that the initial attempt to read the EDID always failed. It takes one retry for the read to succeed. As we are about to remove this automatic retry property from i2c-algo-bit, reading the EDID would really fail. As a summary, the I2C lines quirk which is supposedly needed to read EDID on some older monitors is currently breaking the (first) read on all other monitors (and might not even work with older ones - did anyone try since October 2006?) After applying the patch below, which makes the code in fb_ddc_read() really similar to what the radeon driver used to have, the first EDID read succeeds again. On top of that, as it appears that this code has been broken for one year now and nobody seems to have complained, I'm curious if it makes sense to keep this quirk in place. It makes the code more complex and slower just for the sake of monitors which I guess nobody uses anymore. Can't we just get rid of it? Signed-off-by: Jean Delvare <khali@linux-fr.org> Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Tested-by: Roger Leigh <rleigh@whinlatter.ukfsn.org> Tested-by: Michael Buesch <mb@bu3sch.de> Cc: "Antonino A. Daplas" <adaplas@pol.net> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Fix generic fb_ddc i2c edid probe msgLinus Torvalds2006-11-161-3/+3
| | | | | | | | | | | | | Benh points out that the msgs[0].flags entry never got initialized, and since it's an automatic stack allocation, it could have any random value, which is bad. Rewrite the initializer to explicitly initialize all fields of the small i2c_msg structure array we generate. Just to keep it all obvious, let's handle msgs[1].buf in the same initializer while we're at it, instead of initializing that one separately later. Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] fbdev: Add generic ddc read functionalityDennis Munsie2006-10-031-0/+116
Adds functionality to read the EDID information over the DDC bus in a generic way. This code is based on the DDC implementation in the radeon driver. [adaplas] - separate from fbmon.c and place in new file fb_ddc.c - remove dependency to CONFIG_I2C and CONFIG_I2C_ALGOBIT, otherwise, feature will not compile if i2c support is compiled as a module - feature is selectable only by drivers needing it. It must have a 'select FB_DDC if xxx' in Kconfig - change printk's to dev_*, the i2c people prefers it Signed-off-by: Dennis Munsie <dmunsie@cecropia.com> Signed-off-by: Antonino Daplas <adaplas@pol.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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