Hi, On Mon, 15 Apr 2019 at 16:51, Maxime Ripard <maxime.ripard@xxxxxxxxxxx> wrote: > > On Mon, Apr 15, 2019 at 10:30:38AM +0200, Clément Péron wrote: > > On Mon, 15 Apr 2019 at 10:18, Maxime Ripard <maxime.ripard@xxxxxxxxxxx> wrote: > > > > > > On Mon, Apr 15, 2019 at 10:09:11AM +0200, Clément Péron wrote: > > > > Hi, > > > > > > > > On Mon, 15 Apr 2019 at 10:04, Maxime Ripard <maxime.ripard@xxxxxxxxxxx> wrote: > > > > > > > > > > Hi, > > > > > > > > > > On Thu, Apr 11, 2019 at 11:44:19PM +0200, Clément Péron wrote: > > > > > > Allwinner H6 has a SPDIF controller with an increase of the fifo > > > > > > size and the possibility to output the master clock. > > > > > > However it's still compatible with the already existing driver for > > > > > > Allwiner H3. > > > > > > > > > > > > Add this compatible in the device-tree bindings documentation. > > > > > > > > > > How was this tested? > > > > > > > > Using Alsa utils on a Beelink GS1 and I check correct output sound on > > > > my home cinema. > > > > > > > > > After looking at the datasheet, it looks like it's still significantly > > > > > different. In particular: > > > > > > > > > > - The MCLK divider isn't at the same offset > > > > > > > > We don't use the MCLK > > > > > > > > > - The bits to flush the FIFO aren't at the same offset > > > > > - The FIFO trigger levels aren't at the same offset > > > > > - The FIFO status register layout is almost entirely different > > > > > > > > We use DMA not FIFO > > > > > > Well, DMA still uses the FIFOs. And even then, you're kind of missing > > > the point. The device tree's compatible is about whether a particular > > > device can be used as another one. How you are using it in the driver > > > is completely irrelevant. > > > > Sorry I meant " We use DMA not PIO". > > I'm still not quite sure what you mean. Both DMA and PIO would be > using the FIFOs. Just correcting myself but yes we use FIFO with the DMA. > > > I didn't change the driver and the SPDIF is working what's irrelevant > > in declaring the driver as compatible ? > > It's working by accident. > > This won't work for example: > https://elixir.bootlin.com/linux/latest/source/sound/soc/sunxi/sun4i-spdif.c#L181 > > > If some feature are missing they can be introduce later as there is a > > special binding for H6 no ? > > Again, that's irrelevant. The only question you need to ask yourself > is whether, if you take an imaginary source code that would support > all the H3 SPDIF features and run it on an H6, it works just as well. > > The examples above that it's not the case, so you can't claim that the > device is compatible. Is it ok if I fix the TX Fifo flush bit and remove the compatible with H3 ? (Looking at the driver this is the only bit used that is incompatible with H6) Or should I send a new driver with the correct mapping ? Thanks Clément > > Maxime > > -- > Maxime Ripard, Bootlin > Embedded Linux and Kernel engineering > https://bootlin.com
