Hi Dirk-san, > From: Dirk Behme, Sent: Tuesday, October 17, 2017 2:08 PM > > Limiting the thread to Renesas only, again, to discuss the other issue: > > On 17.10.2017 06:51, Yoshihiro Shimoda wrote: > > 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. > > > Great, many thanks! I'll try to test that in the next days, then. > > While above fixes the swiotlb full issue, we still have the issue that > it looks like the driver doesn't handle that issue correctly and > crashes, then: > > renesas_sdhi_internal_dmac ee100000.sd: DMA: Out of SW-IOMMU space for > 524288 bytes > -> Unable to handle kernel paging request at virtual address > ffffffffc0000000 <- > > I'd propose to fix that, too. Have you looked into that issue, too? > > I'm no expert on this, but it looks to me that other drivers are > checking the return value of dma_map_sg() differently? > > ret = dma_map_sg(&host->pdev->dev, sg, host->sg_len, dir); > if (ret < 0) > return; > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/mmc/host/renesas_sdhi_internal_dmac. > c#n165 > > They check for (ret == 0)? > > Sorry if I'm wrong on that ;) Thank you for the comments! You're correct. We should check for (ret == 0) at least. I also think we should set host->force_pio = true and call renesas_sdhi_internal_dmac_enable_dma(host, false) to do PIO if "ret == 0". I will make such a patch and submit it. Best regards, Yoshihiro Shimoda > Best regards > > Dirk
