On Sun, 22 Nov 2009 19:17:59 -0500, Andy Walls wrote: > On Sun, 2009-11-22 at 21:32 +0100, Jean Delvare wrote: > > The fact that 0x30-0x37 and 0x50-0x5f all reply suggest that the bus > > driver erroneously returns success to "SMBus receive byte" transactions > > even when no device acks. This is a bug which should get fixed. If you > > point me to the I2C adapter driver code, I can take a look. > > Although Igor's information makes the original need for this moot, here > is the i2c adapter driver code: > > http://linuxtv.org/hg/v4l-dvb/file/8bff7e6c44d4/linux/drivers/media/video/cx23885/cx23885-i2c.c The results are not surprising: i2c_slave_did_ack() is only called for zero-length transactions. For all other transactions, no check is done. This is incorrect. I have written 3 patches for cx23885-i2c.c, the second one should fix this particular issue. The other two are cleanups. Patches are there if you want to take a look / give them a try: http://khali.linux-fr.org/devel/misc/cx23885/ These are totally untested, and I don't know anything about the hardware, so they might need some more work. But at least you should get the idea of what's missing. > Note the CX2388[578] chips have 3 I2C masters, 2 for external buses, and > 1 internal "on silicon" bus which the driver sets up as the 3rd bus. > The internal bus should at least have devices at 0x44 and 0x4c as > confirmed above. I'll note the comment in this file, that indicates the > "on silicon" I2C bus runs at 1.95 MHz: > > http://linuxtv.org/hg/v4l-dvb/file/8bff7e6c44d4/linux/drivers/media/video/cx23885/cx23885-core.c This is strange. For one thing, 1.95 MHz wouldn't be standard I2C but high-speed mode I2C. But more importantly, I fail to see how you could reach such speeds with a software-driven, byte-by-byte implementation. You need hardware buffers to reach high speeds on I2C. > The TeVii S470 card had what looked like at serial I2C EEPROM with the > A0, A1, and A2 pins all grounded, so I assume it is at 0x50 on one of > the CX23885's external I2C buses. Probably. Hopefully my patches will show you where it is. -- Jean Delvare -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
