[v2,1/2] mmc: tmio: fix swiotlb buffer is full
diff mbox

Message ID 1508469162-12322-2-git-send-email-yoshihiro.shimoda.uh@renesas.com
State New
Headers show

Commit Message

Yoshihiro Shimoda Oct. 20, 2017, 3:12 a.m. UTC
Since the commit de3ee99b097d ("mmc: Delete bounce buffer handling")
deletes the bounce buffer handling, a request data size will be referred
to max_{req,seg}_size instead of MMC_QUEUE_BOUNCESZ (64k bytes).

In other hand, renesas_sdhi_internal_dmac.c will set very big value of
max_{req,seg}_size because the max_blk_count is set to 0xffffffff.
And then, "swiotlb buffer is full" happens because swiotlb can handle
a memory size up to 256k bytes only (IO_TLB_SEGSIZE = 128 and
IO_TLB_SHIFT = 11).

So, as a workaround, this patch avoids the issue by setting
the max_{req,seg}_size up to 256k bytes if swiotlb is running.

Reported-by: Dirk Behme <dirk.behme@de.bosch.com>
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
---
 drivers/mmc/host/tmio_mmc_core.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

Comments

Wolfram Sang Oct. 20, 2017, 4 a.m. UTC | #1
On Fri, Oct 20, 2017 at 12:12:41PM +0900, Yoshihiro Shimoda wrote:
> Since the commit de3ee99b097d ("mmc: Delete bounce buffer handling")
> deletes the bounce buffer handling, a request data size will be referred
> to max_{req,seg}_size instead of MMC_QUEUE_BOUNCESZ (64k bytes).
> 
> In other hand, renesas_sdhi_internal_dmac.c will set very big value of
> max_{req,seg}_size because the max_blk_count is set to 0xffffffff.
> And then, "swiotlb buffer is full" happens because swiotlb can handle
> a memory size up to 256k bytes only (IO_TLB_SEGSIZE = 128 and
> IO_TLB_SHIFT = 11).
> 
> So, as a workaround, this patch avoids the issue by setting
> the max_{req,seg}_size up to 256k bytes if swiotlb is running.
> 
> Reported-by: Dirk Behme <dirk.behme@de.bosch.com>
> Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>

For the issues we are seeing with v4.14, I think this fix is good. We
plan to fully fix this issue at a more generic level, then this addition
can go again. But we are not there yet, and likely need some additional
API, so:

Acked-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Geert Uytterhoeven Oct. 20, 2017, 7:29 a.m. UTC | #2
On Fri, Oct 20, 2017 at 5:12 AM, Yoshihiro Shimoda
<yoshihiro.shimoda.uh@renesas.com> wrote:
> Since the commit de3ee99b097d ("mmc: Delete bounce buffer handling")
> deletes the bounce buffer handling, a request data size will be referred
> to max_{req,seg}_size instead of MMC_QUEUE_BOUNCESZ (64k bytes).
>
> In other hand, renesas_sdhi_internal_dmac.c will set very big value of
> max_{req,seg}_size because the max_blk_count is set to 0xffffffff.
> And then, "swiotlb buffer is full" happens because swiotlb can handle
> a memory size up to 256k bytes only (IO_TLB_SEGSIZE = 128 and
> IO_TLB_SHIFT = 11).
>
> So, as a workaround, this patch avoids the issue by setting
> the max_{req,seg}_size up to 256k bytes if swiotlb is running.
>
> Reported-by: Dirk Behme <dirk.behme@de.bosch.com>
> Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>

Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds
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Patch
diff mbox

diff --git a/drivers/mmc/host/tmio_mmc_core.c b/drivers/mmc/host/tmio_mmc_core.c
index a7293e1..9c4e619 100644
--- a/drivers/mmc/host/tmio_mmc_core.c
+++ b/drivers/mmc/host/tmio_mmc_core.c
@@ -47,6 +47,7 @@ 
 #include <linux/mmc/sdio.h>
 #include <linux/scatterlist.h>
 #include <linux/spinlock.h>
+#include <linux/swiotlb.h>
 #include <linux/workqueue.h>
 
 #include "tmio_mmc.h"
@@ -1215,6 +1216,18 @@  int tmio_mmc_host_probe(struct tmio_mmc_host *_host,
 	mmc->max_blk_count = pdata->max_blk_count ? :
 		(PAGE_SIZE / mmc->max_blk_size) * mmc->max_segs;
 	mmc->max_req_size = mmc->max_blk_size * mmc->max_blk_count;
+	/*
+	 * Since swiotlb has memory size limitation, this will calculate
+	 * the maximum size locally (because we don't have any APIs for it now)
+	 * and check the current max_req_size. And then, this will update
+	 * the max_req_size if needed as a workaround.
+	 */
+	if (swiotlb_max_segment()) {
+		unsigned int max_size = (1 << IO_TLB_SHIFT) * IO_TLB_SEGSIZE;
+
+		if (mmc->max_req_size > max_size)
+			mmc->max_req_size = max_size;
+	}
 	mmc->max_seg_size = mmc->max_req_size;
 
 	_host->native_hotplug = !(pdata->flags & TMIO_MMC_USE_GPIO_CD ||