2022-05-16 21:40:32 +00:00
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From b70da899940777d92338d8f83f7a6236818ad08a Mon Sep 17 00:00:00 2001
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From: Jonathan Bell <jonathan@raspberrypi.com>
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Date: Mon, 16 May 2022 10:28:27 +0100
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Subject: [PATCH] mmc: block: Don't do single-sector reads during
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recovery
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See https://github.com/raspberrypi/linux/issues/5019
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If an SD card has degraded performance such that IO operations time out
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then the MMC block layer will leak SG DMA mappings in the swiotlb during
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recovery. It retries the same SG and this causes the leak, as it is
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mapped twice - once in sdhci_pre_req() and again during single-block
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reads in sdhci_prepare_data().
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Resetting the card (including power-cycling if a regulator for vmmc is
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present) ought to be enough to recover a stuck state, so for now don't
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try single-block reads in the recovery path.
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Signed-off-by: Jonathan Bell <jonathan@raspberrypi.com>
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---
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drivers/mmc/core/block.c | 6 +++++-
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1 file changed, 5 insertions(+), 1 deletion(-)
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--- a/drivers/mmc/core/block.c
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+++ b/drivers/mmc/core/block.c
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2022-06-20 09:50:45 +00:00
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@@ -1870,7 +1870,11 @@ static void mmc_blk_mq_rw_recovery(struc
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2022-05-16 21:40:32 +00:00
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}
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/* FIXME: Missing single sector read for large sector size */
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- if (!mmc_large_sector(card) && rq_data_dir(req) == READ &&
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+ /*
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+ * XXX: don't do single-sector reads, as it leaks a SG DMA
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+ * mapping when reusing the still-pending req.
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+ */
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+ if (0 && !mmc_large_sector(card) && rq_data_dir(req) == READ &&
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brq->data.blocks > 1) {
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/* Read one sector at a time */
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mmc_blk_read_single(mq, req);
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