On Thu, Oct 17, 2019 at 10:06:38AM +0300, Andy Shevchenko wrote: > On Thu, Oct 17, 2019 at 08:44:26AM +0200, Daniel Vetter wrote: > > In DMA mode we have a maximum transfer size, past that the driver > > falls back to PIO (see the check at the top of pxa2xx_spi_transfer_one). > > Falling back to PIO for big transfers defeats the point of a dma engine, > > hence set the max transfer size to inform spi clients that they need > > to do something smarter. > > > > This was uncovered by the drm_mipi_dbi spi panel code, which does > > large spi transfers, but stopped splitting them after: > > > > commit e143364b4c1774f68e923a5a0bb0fca28ac25888 > > Author: Noralf Trønnes <noralf@xxxxxxxxxxx> > > Date: Fri Jul 19 17:59:10 2019 +0200 > > > > drm/tinydrm: Remove tinydrm_spi_max_transfer_size() > > > > After this commit the code relied on the spi core to split transfers > > into max dma-able blocks, which also papered over the PIO fallback issue. > > > > Fix this by setting the overall max transfer size to the DMA limit, > > but only when the controller runs in DMA mode. > > > > Thank you, Daniel! Mark, can be this applied? -- With Best Regards, Andy Shevchenko _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
