[PATCH 4/4] mmc: meson-gx: add CMD23 mode

[Heiner Kallweit]

CMD23 mode (use "set block count" command before transferring multiple
data blocks) typically is more performant as host / card know upfront
how many data blocks to expect. Therefore add support for this mode to
the driver.

Signed-off-by: Heiner Kallweit <hkallweit1 at gmail.com>
---
 drivers/mmc/host/meson-gx-mmc.c | 21 +++++++++++++++++----
 1 file changed, 17 insertions(+), 4 deletions(-)

diff --git a/drivers/mmc/host/meson-gx-mmc.c b/drivers/mmc/host/meson-gx-mmc.c
index e637b3ba..6e93270f 100644
--- a/drivers/mmc/host/meson-gx-mmc.c
+++ b/drivers/mmc/host/meson-gx-mmc.c
@@ -181,6 +181,17 @@ static unsigned int meson_mmc_get_timeout(struct mmc_data *data)
 	return min(timeout, 32768U); /* max. 2^15 ms */
 }
 
+static struct mmc_command *meson_mmc_get_next_command(struct mmc_command *cmd)
+{
+	if (cmd->opcode == MMC_SET_BLOCK_COUNT && !cmd->error)
+		return cmd->mrq->cmd;
+	else if (mmc_op_multi(cmd->opcode) &&
+		 (!cmd->mrq->sbc || cmd->error || cmd->data->error))
+		return cmd->mrq->stop;
+	else
+		return NULL;
+}
+
 static int meson_mmc_clk_set(struct meson_host *host, unsigned long clk_rate)
 {
 	struct mmc_host *mmc = host->mmc;
@@ -626,7 +637,7 @@ static irqreturn_t meson_mmc_irq(int irq, void *dev_id)
 static irqreturn_t meson_mmc_irq_thread(int irq, void *dev_id)
 {
 	struct meson_host *host = dev_id;
-	struct mmc_command *cmd = host->cmd;
+	struct mmc_command *next_cmd, *cmd = host->cmd;
 	struct mmc_data *data;
 	unsigned int xfer_bytes;
 
@@ -641,10 +652,11 @@ static irqreturn_t meson_mmc_irq_thread(int irq, void *dev_id)
 				    host->bounce_buf, xfer_bytes);
 	}
 
-	if (!data || !data->stop || cmd->mrq->sbc)
-		meson_mmc_request_done(host->mmc, cmd->mrq);
+	next_cmd = meson_mmc_get_next_command(cmd);
+	if (next_cmd)
+		meson_mmc_start_cmd(host->mmc, next_cmd);
 	else
-		meson_mmc_start_cmd(host->mmc, data->stop);
+		meson_mmc_request_done(host->mmc, cmd->mrq);
 
 	return IRQ_HANDLED;
 }
@@ -756,6 +768,7 @@ static int meson_mmc_probe(struct platform_device *pdev)
 	if (ret)
 		goto err_div_clk;
 
+	mmc->caps |= MMC_CAP_CMD23;
 	mmc->max_blk_count = CMD_CFG_LENGTH_MASK;
 	mmc->max_req_size = mmc->max_blk_count * mmc->max_blk_size;
 
-- 
2.12.0