On Fri, Jul 19, 2019 at 05:59:10PM +0200, Noralf Trønnes wrote: > spi-bcm2835 can handle >64kB buffers now so there is no need to check > ->max_dma_len. The tinydrm_spi_max_transfer_size() max_len argument is > not used by any callers, so not needed. > > Then we have the spi_max module parameter. It was added because > staging/fbtft has support for it and there was a report that someone used > it to set a small buffer size to avoid popping on a USB soundcard on a > Raspberry Pi. In hindsight it shouldn't have been added, I should have > waited for it to become a problem first. I don't know it anyone is > actually using it, but since tinydrm_spi_transfer() is being moved to > mipi-dbi, I'm taking the opportunity to remove it. I'll add it back to > mipi-dbi if someone complains. > > With that out of the way, spi_max_transfer_size() can be used instead. > > The chosen 16kB buffer size for Type C Option 1 (9-bit) interface is > somewhat arbitrary, but a bigger buffer will have a miniscule impact on > transfer speed, so it's probably fine. This breaks the SPI PXA2xx case I'm using. The world is not a Pi:e. [ 388.445752] mi0283qt spi-PRP0001:01: DMA disabled for transfer length 153600 greater than 65536 [ 388.634437] mi0283qt spi-PRP0001:01: DMA disabled for transfer length 153600 greater than 65536 [ 388.822933] mi0283qt spi-PRP0001:01: DMA disabled for transfer length 153600 greater than 65536 The crucial thing is to check the transfer size against maximum DMA length of the master. Please, fix. -- With Best Regards, Andy Shevchenko _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
