Hi Jay, Am Montag, 25. Januar 2016, 09:15:31 schrieb Jianqun Xu: > ? 23/01/2016 01:18, Mark Brown ??: > > On Fri, Jan 15, 2016 at 01:48:04PM -0800, Sonny Rao wrote: > >> On Fri, Jan 15, 2016 at 9:46 AM, Mark Brown <broonie at kernel.org> wrote: > >>> If the I2S block is providing a clock to the CODEC then that's what the > >>> software should do so that the CODEC can gate and ungate the clock as > >>> required. This patch has the I2S block using a clock, not providing > >>> one. > >>> > >> From my read of the clock diagram for RK3288 there is a single clock > >> > >> signal (labeled "clk_i2s0") that comes out of a fractional divider, > >> and it is split such that one path gets sent to the I2S block and the > >> second path is sent to a mux after which that signal is sent to an > >> external pin that goes to the codec. > >> > >> There are separate clock gates for the two paths: one for the I2S > >> block and one after that mux before the external pin. > >> > >> I'm not sure if it's being modeled that way in the Linux code or not, > >> but at least physically I don't think this clock signal actually goes > >> through the I2S block before being sent to the codec. > > > > That's not really the issue here, the issue is that it's not the I2S > > controller that is consuming the clock so it should not be the I2S > > controller driver that ensures that the clock is enabled. The driver > > that manages the clock should be the one that uses it, like I say this > > means you should add the code to enable the clock to the CODEC driver if > > the CODEC driver needs the clock enabled. > > Agree, now we almost use the simple-card for the CODEC driver, so I > think we should enable the mclk(i2s-outclk) in the simple-card driver, > is it ? > > I found a subnode property from simple-card document: > - mclk-fs : Multiplication factor between > stream > rate and codec mclk, applied > only for > the dai-link. > But the property responsible to the factor, not care if the mclk source > clock is enabled or not. So does the simple-card driver can add support > to enable/disable mclk ? The mclk-input is part of the codec I'd think. So you'd want the clocks- property in the i2c entry describing the codec itself and implement the clk operations in the codec driver as well. See codec-drivers for da7213, da7218,max98090 and many more for reference. Heiko > >> Does that help clarify? > > > > The problem here isn't a lack of clarity in the situation.
