On Tue, Apr 10, 2012 at 6:41 PM, Daniel Vetter <daniel@xxxxxxxx> wrote: > On Tue, Apr 10, 2012 at 12:37:46PM +0200, Daniel Vetter wrote: >> On Fri, Mar 30, 2012 at 07:46:39PM +0800, Daniel Kurtz wrote: >> > The i915 is only able to generate a STOP cycle (i.e. finalize an i2c >> > transaction) during a DATA or WAIT phase. In other words, the >> > controller rejects a STOP requested as part of the first transaction in a >> > sequence. >> > >> > Thus, for the first transaction we must always use a WAIT cycle, detect >> > when the device has finished (and is in a WAIT phase), and then either >> > start the next transaction, or, if there are no more transactions, >> > generate a STOP cycle. >> > >> > Note: Theoretically, the last transaction of a multi-transaction sequence >> > could initiate a STOP cycle. However, this slight optimization is left >> > for another patch. We return -ETIMEDOUT if the hardware doesn't >> > deactivate after the STOP cycle. >> > >> > Signed-off-by: Daniel Kurtz <djkurtz@xxxxxxxxxxxx> >> >> I've re-read gmbus register spec and STOP seems to be allowed even in the >> first cycle. Does this patch solve an issue for you? If not, I prefer we >> just drop it. STOP does not work in the first cycle, hence the patch. -Daniel > > Actually I'd like to keep the -ETIMEDOUT return value, so maybe we should > keeep that hunk. I've picked up the previous 3 patches of this series, the > once after this one here conflict (without this patch here). > -Daniel > -- > Daniel Vetter > Mail: daniel@xxxxxxxx > Mobile: +41 (0)79 365 57 48 _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/dri-devel
