Hi Linus-san, > From: Linus Walleij, Sent: Monday, October 16, 2017 9:22 PM > > On Mon, Oct 16, 2017 at 2:07 PM, Geert Uytterhoeven > <geert@xxxxxxxxxxxxxx> wrote: > > On Mon, Oct 16, 2017 at 1:41 PM, Linus Walleij <linus.walleij@xxxxxxxxxx> wrote: > >> On Mon, Oct 16, 2017 at 11:02 AM, Geert Uytterhoeven > >> <geert@xxxxxxxxxxxxxx> wrote: > >>>> IIUC, > >>>> - Since the MMC_BOUNCE disappeared in v4.14-rc1, the MMC core will request a command with 64kbyte+ size. > >>>> - So, swiotlb will got request 64kbyte+ size. This is different with previous version. > >> > >> Other people reported problems with that. Sorry about this... > >> > >> This problem should be solved by upstream > >> commit de3ee99b097dd51938276e3af388cd4ad0f2750a > >> "mmc: Delete bounce buffer handling" > >> > >> I just killed off the bounce buffers so they can't hurt anyone anymore. > >> > >> Can you check that you have this patch in your tree? > > > > Given Dirk saw the issue with v4.14-rc4, I'm afraid that patch is already > > included :-( > > So the first issue is definately gone. > > Then it seems the driver is specifying to high ->max_seg_size > since the buffer cannot be mapped? > > Unless you're using ADMA drivers/mmc/host/sdhci.c sets it as: > mmc->max_seg_size = mmc->max_req_size; Thank you for the comment! On R-Car Gen3, it's using drivers/mmc/host/renesas_sdhi_internal_dmac.c, and sets the max_seg_size to very big size (0xffffffff * 512) now... So, I modified the value to 262144 and rebase the kernel to v4.14-rc5 (-rc4 seems have other issue in block driver.), the "swiotlb buffer is full" issue disappeared. > And: > mmc->max_req_size = 524288; > > >> renesas_sdhi_internal_dmac ee100000.sd: swiotlb_tbl_map_single: test: > >> size modified to 524288 bytes > >> renesas_sdhi_internal_dmac ee100000.sd: swiotlb buffer is full (sz: > >> 524288 bytes) > > So if your driver cannot handle 524288 bytes, why is it saying it can > handle 524288 bytes? I think the "swiotlb buffer is full" came from lib/swiotlb.c. I'm not sure the detail of swiotlb.c, but IIUC, it has a memory size limitation. - In lib/swiotlb.c, it calculates nslots. - The size of one slot is 2048 bytes because IO_TLB_SHIFT in include/linux/swiotlb.h is set to 11. - IO_TLB_SEGSIZE is set to 128 in include/linux/swiotlb.h. - This value is number of maximum slots. - So, maximum size for a single map of swiotlb is 256kbytes (2048 * 128). So, I will submit a patch to set the max_req_size to 256kbytes today. Best regards, Yoshihiro Shimoda
