[RFC] mmc: meson-gx: use memcpy_to/fromio for dram-access-quirk
From: Neil Armstrong <hidden>
Date: 2021-06-08 15:35:08
Also in:
linux-amlogic, linux-mmc, lkml
Subsystem:
arm/amlogic meson soc support, multimedia card (mmc), secure digital (sd) and sdio subsystem, the rest · Maintainers:
Neil Armstrong, Kevin Hilman, Ulf Hansson, Linus Torvalds
It has been reported that usage of memcpy() to/from an iomem mapping is invalid,
and and recent arm64 memcpy update [1] triggers a memory abort when dram-access-quirk
is used on the G12A/G12B platforms.
This adds a local sg_copy_to_buffer which makes usage of io versions of memcpy
when dram-access-quirk is enabled.
Fixes: acdc8e71d9bb ("mmc: meson-gx: add dram-access-quirk")
Reported-by: Marek Szyprowski <m.szyprowski@samsung.com>
Suggested-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Neil Armstrong <redacted>
[1] 285133040e6c ("arm64: Import latest memcpy()/memmove() implementation")
Signed-off-by: Neil Armstrong <redacted>
---
Hi Ulf, Marek, Mark,
I haven't tested the patch yet, but should fix issue reported at [2].
Neil
[2] https://lore.kernel.org/r/acb244ad-0759-5a96-c659-5c23003d3dcd@samsung.com (local)
drivers/mmc/host/meson-gx-mmc.c | 48 ++++++++++++++++++++++++++++++---
1 file changed, 44 insertions(+), 4 deletions(-)
diff --git a/drivers/mmc/host/meson-gx-mmc.c b/drivers/mmc/host/meson-gx-mmc.c
index b8b771b643cc..89ff6038092d 100644
--- a/drivers/mmc/host/meson-gx-mmc.c
+++ b/drivers/mmc/host/meson-gx-mmc.c@@ -742,6 +742,48 @@ static void meson_mmc_desc_chain_transfer(struct mmc_host *mmc, u32 cmd_cfg) writel(start, host->regs + SD_EMMC_START); } +/* local sg copy to buffer version with _to/fromio usage for dram_access_quirk */ +static void meson_mmc_copy_buffer(struct meson_host *host, struct mmc_data *data, + size_t buflen, bool to_buffer) +{ + unsigned int sg_flags = SG_MITER_ATOMIC; + struct scatterlist *sgl = data->sg; + unsigned int nents = data->sg_len; + struct sg_mapping_iter miter; + void *buf = host->bounce_buf; + unsigned int offset = 0; + + if (to_buffer) + sg_flags |= SG_MITER_FROM_SG; + else + sg_flags |= SG_MITER_TO_SG; + + sg_miter_start(&miter, sgl, nents, sg_flags); + + while ((offset < buflen) && sg_miter_next(&miter)) { + unsigned int len; + + len = min(miter.length, buflen - offset); + + /* When dram_access_quirk, the bounce buffer is a iomem mapping */ + if (host->dram_access_quirk) { + if (to_buffer) + memcpy_toio(buf + offset, miter.addr, len); + else + memcpy_fromio(miter.addr, buf + offset, len); + } else { + if (to_buffer) + memcpy(buf + offset, miter.addr, len); + else + memcpy(miter.addr, buf + offset, len); + } + + offset += len; + } + + sg_miter_stop(&miter); +} + static void meson_mmc_start_cmd(struct mmc_host *mmc, struct mmc_command *cmd) { struct meson_host *host = mmc_priv(mmc);
@@ -785,8 +827,7 @@ static void meson_mmc_start_cmd(struct mmc_host *mmc, struct mmc_command *cmd) if (data->flags & MMC_DATA_WRITE) { cmd_cfg |= CMD_CFG_DATA_WR; WARN_ON(xfer_bytes > host->bounce_buf_size); - sg_copy_to_buffer(data->sg, data->sg_len, - host->bounce_buf, xfer_bytes); + meson_mmc_copy_buffer(host, data, xfer_bytes, true); dma_wmb(); }
@@ -955,8 +996,7 @@ static irqreturn_t meson_mmc_irq_thread(int irq, void *dev_id) if (meson_mmc_bounce_buf_read(data)) { xfer_bytes = data->blksz * data->blocks; WARN_ON(xfer_bytes > host->bounce_buf_size); - sg_copy_from_buffer(data->sg, data->sg_len, - host->bounce_buf, xfer_bytes); + meson_mmc_copy_buffer(host, data, xfer_bytes, false); } next_cmd = meson_mmc_get_next_command(cmd);
--
2.25.1
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