2022-01-06 10:54:58

by Rong Chen

Subject: [PATCH] mmc: meson: Fix usage of meson_mmc_post_req()

To ensure the DMA moves data correctly from memory to
peripherals, DMA unmapping when the MMC request done
with calls meson_mmc_post_req().

Signed-off-by: Rong Chen <[email protected]>
---
drivers/mmc/host/meson-gx-mmc.c | 14 +++++++-------
1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/drivers/mmc/host/meson-gx-mmc.c b/drivers/mmc/host/meson-gx-mmc.c
index 8f36536cb1b6..6a9554ae4b1c 100644
--- a/drivers/mmc/host/meson-gx-mmc.c
+++ b/drivers/mmc/host/meson-gx-mmc.c
@@ -173,6 +173,7 @@ struct meson_host {
int irq;

bool vqmmc_enabled;
+ bool needs_pre_post_req;
};

#define CMD_CFG_LENGTH_MASK GENMASK(8, 0)
@@ -663,6 +664,8 @@ static void meson_mmc_request_done(struct mmc_host *mmc,
struct meson_host *host = mmc_priv(mmc);

host->cmd = NULL;
+ if (host->needs_pre_post_req)
+ meson_mmc_post_req(mmc, mrq, 0);
mmc_request_done(host->mmc, mrq);
}

@@ -880,7 +883,7 @@ static int meson_mmc_validate_dram_access(struct mmc_host *mmc, struct mmc_data
static void meson_mmc_request(struct mmc_host *mmc, struct mmc_request *mrq)
{
struct meson_host *host = mmc_priv(mmc);
- bool needs_pre_post_req = mrq->data &&
+ host->needs_pre_post_req = mrq->data &&
!(mrq->data->host_cookie & SD_EMMC_PRE_REQ_DONE);

/*
@@ -896,22 +899,19 @@ static void meson_mmc_request(struct mmc_host *mmc, struct mmc_request *mrq)
}
}

- if (needs_pre_post_req) {
+ if (host->needs_pre_post_req) {
meson_mmc_get_transfer_mode(mmc, mrq);
if (!meson_mmc_desc_chain_mode(mrq->data))
- needs_pre_post_req = false;
+ host->needs_pre_post_req = false;
}

- if (needs_pre_post_req)
+ if (host->needs_pre_post_req)
meson_mmc_pre_req(mmc, mrq);

/* Stop execution */
writel(0, host->regs + SD_EMMC_START);

meson_mmc_start_cmd(mmc, mrq->sbc ?: mrq->cmd);
-
- if (needs_pre_post_req)
- meson_mmc_post_req(mmc, mrq, 0);
}

static void meson_mmc_read_resp(struct mmc_host *mmc, struct mmc_command *cmd)

base-commit: 356f3f2c5756bbb67a515760966a40fc7043cdda
--
2.25.1

2022-01-25 08:38:10

by Kevin Hilman

Subject: Re: [PATCH] mmc: meson: Fix usage of meson_mmc_post_req()

Hello Rong,

First, thank you finding the issue and for submitting a fix!

Rong Chen <[email protected]> writes:

> To ensure the DMA moves data correctly from memory to
> peripherals, DMA unmapping when the MMC request done
> with calls meson_mmc_post_req().
>
> Signed-off-by: Rong Chen <[email protected]>

The patch looks correct, but I think I think the changelog could be
improved. If I understand the code correctly, I think what you're doing
is:

"""
Currently meson_mmc_post_req() is called in meson_mmc_request() right
after _start_cmd(). This could lead to DMA unmapping before the request
is actually finished.

To fix, ton't call meson_mmc_post_req() until _request_done().
"""

Kevin

> ---
> drivers/mmc/host/meson-gx-mmc.c | 14 +++++++-------
> 1 file changed, 7 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/mmc/host/meson-gx-mmc.c b/drivers/mmc/host/meson-gx-mmc.c
> index 8f36536cb1b6..6a9554ae4b1c 100644
> --- a/drivers/mmc/host/meson-gx-mmc.c
> +++ b/drivers/mmc/host/meson-gx-mmc.c
> @@ -173,6 +173,7 @@ struct meson_host {
> int irq;
>
> bool vqmmc_enabled;
> + bool needs_pre_post_req;
> };
>
> #define CMD_CFG_LENGTH_MASK GENMASK(8, 0)
> @@ -663,6 +664,8 @@ static void meson_mmc_request_done(struct mmc_host *mmc,
> struct meson_host *host = mmc_priv(mmc);
>
> host->cmd = NULL;
> + if (host->needs_pre_post_req)
> + meson_mmc_post_req(mmc, mrq, 0);
> mmc_request_done(host->mmc, mrq);
> }
>
> @@ -880,7 +883,7 @@ static int meson_mmc_validate_dram_access(struct mmc_host *mmc, struct mmc_data
> static void meson_mmc_request(struct mmc_host *mmc, struct mmc_request *mrq)
> {
> struct meson_host *host = mmc_priv(mmc);
> - bool needs_pre_post_req = mrq->data &&
> + host->needs_pre_post_req = mrq->data &&
> !(mrq->data->host_cookie & SD_EMMC_PRE_REQ_DONE);
>
> /*
> @@ -896,22 +899,19 @@ static void meson_mmc_request(struct mmc_host *mmc, struct mmc_request *mrq)
> }
> }
>
> - if (needs_pre_post_req) {
> + if (host->needs_pre_post_req) {
> meson_mmc_get_transfer_mode(mmc, mrq);
> if (!meson_mmc_desc_chain_mode(mrq->data))
> - needs_pre_post_req = false;
> + host->needs_pre_post_req = false;
> }
>
> - if (needs_pre_post_req)
> + if (host->needs_pre_post_req)
> meson_mmc_pre_req(mmc, mrq);
>
> /* Stop execution */
> writel(0, host->regs + SD_EMMC_START);
>
> meson_mmc_start_cmd(mmc, mrq->sbc ?: mrq->cmd);
> -
> - if (needs_pre_post_req)
> - meson_mmc_post_req(mmc, mrq, 0);
> }
>
> static void meson_mmc_read_resp(struct mmc_host *mmc, struct mmc_command *cmd)
>
> base-commit: 356f3f2c5756bbb67a515760966a40fc7043cdda
> --
> 2.25.1