On Tue, Mar 15, 2022 at 09:26:01AM +0100, Yann Gautier wrote: > On 3/14/22 23:43, Linus Walleij wrote: > > "On Fri, Mar 4, 2022 at 2:52 PM Yann Gautier <yann.gautier@xxxxxxxxxxx> wrote: > > > > > On STMicroelectronics variant of PL18x, the DMA Linked Lists are supported > > > starting from revision v2 of the peripheral. But it has limitations, > > > as all the buffers should be aligned on block size (except the last one). > > > But this cannot be guaranteed with SDIO. We should then have a property > > > to disable the support of LLI. > > > > > > Signed-off-by: Yann Gautier <yann.gautier@xxxxxxxxxxx> > > > > Actually I think this is present also on the ux500 variants. See: > > commit 2253ed4b36dc876d1598c4dab5587e537ec68c34 > > "mmc: mmci: Support any block sizes for ux500v2 and qcom variant" > > > > Spot the variant data "dma_power_of_2". > > > > So whatever property you add > > to the variant data (not in the device tree please) should > > be added to the ux500 variants as well, it will *VERY* likely > > have a problem with LLI elements not being a power of 2 > > as it is the ancestor of later STMicro variants. > > > > It might actually be the reason for some annoying WiFi error > > messages I have seen :/ > > > > Yours, > > Linus Walleij > > Hi Linus, > > The STM32 variant uses an internal DMA, and the DMA functions are in its > dedicated file. So I was planning to do the same as what is done in > meson-gx-mmc.c: using a bounce buffer to copy from/to in case DMA > constraints are not fulfilled. Not sure it can help for Ux500. > Irrelevant to this patch: May I know why the internal DMA cannot be represented as a dmaengine driver? We started seeing these internal DMA implementations in the other subsystems as well with pointers towards MMC core [1]. Thanks, Mani [1] https://lore.kernel.org/all/CA+V-a8tfUgvzPyMe_FHuz=8mmC6dPHP7E=e+nCzOey04vCcAkg@xxxxxxxxxxxxxx/ > Ulf, before I send my new series (although it is not ready yet), would you > be OK with the bounce buffer idea? > > > Best regards, > Yann
