mmc: meson: Fix usage of meson_mmc_post_req()

commit f0d2f15 upstream.

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

To fix, don't call meson_mmc_post_req() until meson_mmc_request_done().

Signed-off-by: Rong Chen <rong.chen@amlogic.com>
Reviewed-by: Kevin Hilman <khilman@baylibre.com>
Fixes: 79ed05e ("mmc: meson-gx: add support for descriptor chain mode")
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20220216124239.4007667-1-rong.chen@amlogic.com
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/mmc/host/meson-gx-mmc.c

@@ -173,6 +173,8 @@ struct meson_host {
 	int irq;
 
 	bool vqmmc_enabled;
+	bool needs_pre_post_req;
+
 };
 
 #define CMD_CFG_LENGTH_MASK GENMASK(8, 0)
@@ -652,6 +654,8 @@ 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);
 }
 
@@ -869,7 +873,7 @@ 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);
 
 	/*
@@ -885,22 +889,19 @@ 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)