Hi, On 13-03-2017 09:36, Russell King - ARM Linux wrote: > On Mon, Mar 13, 2017 at 10:27:08AM +0100, Neil Armstrong wrote: >> On 03/10/2017 10:35 AM, Romain Perier wrote: >>> Currently, the audio sampler clock is enabled from dw_hdmi_setup() at >>> step E. and is kept enabled for later use. This clock should be enabled >>> and disabled along with the actual audio stream and not always on (that >>> is bad for PM). Futhermore, this might cause sound glitches with some >>> HDMI devices, as the CTS+N is forced to zero when the stream is disabled >>> while the audio clock is still running. >>> >>> This commit adds a parameter to hdmi_audio_enable_clk() that controls >>> when the audio sample clock must be enabled or disabled. Then, it moves >>> the call to this function into dw_hdmi_audio_enable() and >>> dw_hdmi_audio_disable(). >>> >>> Signed-off-by: Romain Perier <romain.perier@xxxxxxxxxxxxx> >>> --- >>> drivers/gpu/drm/bridge/dw-hdmi.c | 15 +++++++++------ >>> 1 file changed, 9 insertions(+), 6 deletions(-) >>> >> Hi Romain, Russell, Jose, >> >> This is a little out of scope, but I was wondering why the CTS calculation >> was not left in AUTO mode in the dw-hdmi driver ? > There is no indication in the iMX6 manuals that the iMX6 supports > automatic CTS calculation. Bits 7:4 of the AUD_CTS3 register are > marked as "reserved". > > We're reliant on the information in the iMX6 manuals as we don't have > access to Synopsis' databooks for these parts (I understand you have > to be a customer to have access to that.) > (Synopsis -> Synopsys :)) Trying to catch up with the conversation: 1) In AHB audio mode the bits are always reserved. 2) I think we should enable/disable clock instead of just forcing N/CTS, though, I don't know what could be the implications for iMX platform. I remember at the time I tested this using I2S (I've never used AHB), and HDMI protocol analyzers were complaining about the N/CTS being forced to zero. 3) I also remember that there was something wrong with the N calculations (I had to remove the if for pixel clock == 25175000). I never submited a patch to that because I was running out of time and didn't investigate this further (it could be for example a problem specific to my setup). Hope it helps a little bit. Best regards, Jose Miguel Abreu _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
