Am Sonntag, 17. Februar 2019, 11:58:36 CET schrieb Katsuhiro Suzuki: > Hello Heiko, > > On 2019/02/12 20:12, Heiko Stübner wrote: > > Hi, > > > > Am Montag, 4. Februar 2019, 13:59:37 CET schrieb Katsuhiro Suzuki: > >> On 2019/02/03 18:06, Heiko Stuebner wrote: > >>> Am Samstag, 2. Februar 2019, 05:34:44 CET schrieb Katsuhiro Suzuki: > >>>> This patch adds HDMI sound (I2S0) node and remove dma properties > >>>> from UART2 node for rock64. > >>>> > >>>> The DMAC of rk3328 can use 8 channels at same time. Currently, total > >>>> > >>>> 7 channels are used as follows: > >>>> - I2S1 2ch > >>>> - UART2 2ch > >>>> - SPDIF 1ch > >>>> - SPI0 2ch > >>>> > >>>> HDMI audio using I2S0 that requires 2ch but DMAC has only 1 channel. > >>>> > >>>> UART2 can work without DMA resources, so this patch removes dma > >>>> allocation for UART2 and reuses it to I2S0. > >>> > >>> I don't follow that description. How can i2s0 re-use the uart2 dma > >>> channels? Looking at the dma table in the TRM, uart2 has channels 6+7 > >>> while i2s0 uses channels 11+12. They should just run concurrently? > >> > >> Sorry for confusing... 6 or 7 is as ID number of slave DMA channel. > >> TRM calls it 'Req number'. Req number 6+7 and 11+12 can work > >> concurrently but TRM says DMAC can transfer 8 DMA channels at same > >> time. So all 16 Req numbers cannot activate at same time. It should > >> be keep less or equal than 8 numbers. > > > > But that "shortcoming" of having more requests than channels is not > > something specific to the pl330, instead most dma controllers have that > > "problem", which seems to get solved by the virt-dma mechanism of > > dmaengine - which pl330 doesn't use so far. (but see pl080 for example) > > > > I understand. I drop these patches. > > > > The devicetree only describes the hardware and is never meant as a > > configuration space for kernel-code shortcomings. > > > > Yes, right. I don't want to use device-tree as configuration space, > so which is better? > > - Fix the pl330 driver first and after that add HDMI-sound node > to device-tree. > - Just add HDMI-sound node to device-tree. If someone (include me) > want to support virt-dma on pl330 driver, they will fix it. > (PL330 will face error but all sounds works fine and UART still > works fine with DMA error) I'd go with this second option :-) . Heiko _______________________________________________ Linux-rockchip mailing list Linux-rockchip@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/linux-rockchip
