> On Jun 12, 2019, at 3:41 AM, Wolfram Sang <wsa@xxxxxxxxxxxxx> wrote: > > On Sat, Jun 08, 2019 at 10:14:43AM -0700, Annaliese McDermond wrote: >> Model the I2C bus clock divider as a part of the Core Clock Framework. >> Primarily this removes the clk_get_rate() call from each transfer. >> This call causes problems for slave drivers that themselves have >> internal clock components that are controlled by an I2C interface. >> When the slave's internal clock component is prepared, the prepare >> lock is obtained, and it makes calls to the I2C subsystem to >> command the hardware to activate the clock. In order to perform >> the I2C transfer, this driver sets the divider, which requires >> it to get the parent clock rate, which it does with clk_get_rate(). >> Unfortunately, this function will try to take the clock prepare >> lock, which is already held by the slave's internal clock calls >> creating a deadlock. >> >> Modeling the divider in the CCF natively removes this dependency >> and the divider value is only set upon changing the bus clock >> frequency or changes in the parent clock that cascade down to this >> divisor. This obviates the need to set the divider with every >> transfer and avoids the deadlock described above. It also should >> provide better clock debugging and save a few cycles on each >> transfer due to not having to recalcuate the divider value. >> >> Signed-off-by: Annaliese McDermond <nh6z@xxxxxxxx> >> Acked-by: Stefan Wahren <stefan.wahren@xxxxxxxx> >> Reviewed-by: Eric Anholt <eric@xxxxxxxxxx> > > Applied to for-next, thanks for keeping at this! Thanks for your patience with this. I know it’s hard to deal with newer folks sometimes, but I really appreciate your forbearance. > And thanks to all > reviewers, too. Thanks too to Eric and Stefan. If you’re ever in the Eugene, OR area look me up for a free beverage of your choice. :) > (One minor thing: next time, please start a new thread when sending a > new patch. This makes applying patches easier.) I’ll definitely do so next time. Thank you. -- Annaliese McDermond nh6z@xxxxxxxx
