Hi Am 12.05.2016 um 11:05 schrieb Wolfram Sang: > Hi Thomas, > > On Wed, Apr 27, 2016 at 08:11:54PM +0200, Thomas Zimmermann wrote: >> Some I2C adapters don't raise SDA by themselves when sending a bit. This >> behavior can be seen with the DDC channel of SiS 300 graphics cards. > > I think you mean 'clients' or 'devices' here, not adapters (masters), > right? Yes, sorry. > So, it seems you have a bus without a pull-up resistor (or a > broken one?) but use now a push-pull design. This is against the I2C > standard and for most circiuts quite dangerous as it can lead to > shortcuts. I see. > Do you have any hints that the bus is designed this way? In which driver > do you want to use the new flag? I was playing with the DRM framework and an old SiS graphics card. I discovered this issue while trying to read the EDID from the monitor. I have a few other SiS cards/models here and they all expose this behavior. So I guess it's intentional(==cheaper?), although the HW docs don't seem mention it explicitly. Best regards Thomas > > Thanks, > > Wolfram > -- GnuPG: http://tdz.users.sourceforge.net/tdz.asc Fingerprint: 16FF F599 82F8 E5AA 18C6 5220 D9DA D7D4 4EF1 DF08 -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
