On Wed, Jan 15, 2014 at 01:27:21PM +0200, Jyri Sarha wrote: > On 12/31/2013 03:25 PM, Mark Brown wrote: > >>support. The only supported sample format is SNDRV_PCM_FORMAT_S32_LE. > >>The 8 least significant bits are ignored. > >Where does this constraint come from? > From driver/gpu/drm/i2c/tda998x_drv.c. The driver configures CTS_N > register statically to a value that works only with 4 byte samples. > According to my tests it is possible to support 3 and 2 byte samples > too by changing the CTS_N register value, but I am not sure if the > configuration can be changed on the fly. My data sheet of the nxp > chip is very vague about the register definitions, but I suppose the > register configures some clock divider on the chip. HDMI supports > only upto 24bit audio and the data sheet states that any extraneous > least significant bits are ignored. Hrm. This sounds like it ought to be presenting as an ASoC CODEC driver. > >>+ snd_pcm_hw_constraint_minmax(runtime, SNDRV_PCM_HW_PARAM_CHANNELS, > >>+ 2, 2); > >Why not just set all this statically when registering the DAI? > Because there is no relevant DAI to where to put these limitations. > I did not want to add yet another dummy codec driver, but decided to > use the already existing ASoC HDMI codec. By default the driver > support all audio params supported by HDMI. The limitations are > coming from NXP chip, the NXP driver, and because the chip is used > in i2s mode. In other words the limitation is coming from machine > setup, not from the DAIs. OK, but it sounds like it's got register configuration as well? That really does sound like a device that ought to have a driver... > No excuse for i initialization, I'll fix that. The casting is just > to survive with just one kmalloc call instead of separate memory > blobs for > struct snd_pcm_hw_constraint_list and referred list of supported > sample rates. I'll allocate a second blob, if that is easier to > read. Yes, please. Unless it's something where memory is getting tight (eg, due to be allocated a lot) it's more important that we can read the code than that we save a few bytes.
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