Hi Onderj, Are you still involved in the s3fb driver? So you still have the hardware to test it? I am looking at the DDC / I2C implementation in that driver and I'm not sure I understand how it works. Specifically I am wondering about bit DDC_DRIVE_EN. It is set unconditionally in s3fb_ddc_setscl() and s3fb_ddc_setsda() and never cleared explicitly. If this bit is a regular bit then I don't understand why it is not just set at driver initialization time. Or is this bit self-clearing and/or not-sticking? The reason why I am asking is that I don't think the code in these functions is completely correct. For the I2C protocol, 1 is the natural state of both lines and the devices on the bus should only ever pull the lines low to force a 0 state. They should never force a 1 state, as this breaks some protocol features (specifically arbitration and clock stretching.) My interpretation of the current code is that the lines are forced to both 0 and 1 by the master, which is not correct. But as I don't know how DDC_DRIVE_EN works, I'm not sure, and if it's indeed broken [1], I'm also not sure how to fix it. So if you could clarify how bit DDC_DRIVE_EN works, that would be great. [1] A broken implementation would work fine in most cases and fail only seldom and randomly, so it could easily go unnoticed. Thanks, -- Jean Delvare SUSE L3 Support -- To unsubscribe from this list: send the line "unsubscribe linux-fbdev" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
