This patch allows transferring of some requests in PIO and some in DMA
mode and defaults to using DMA only for transfers longer than 8 bytes.
This is especially useful with SDIO, which can have lots of 2- and 4-byte
transfers, creating unnecessary high overhead, when executed in DMA.
Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@xxxxxx>
---
drivers/mmc/host/tmio_mmc.c | 33 +++++++++++++++++++++++----------
1 files changed, 23 insertions(+), 10 deletions(-)
diff --git a/drivers/mmc/host/tmio_mmc.c b/drivers/mmc/host/tmio_mmc.c
index aa384ba..f5ec5e6 100644
--- a/drivers/mmc/host/tmio_mmc.c
+++ b/drivers/mmc/host/tmio_mmc.c
@@ -100,6 +100,8 @@
TMIO_STAT_CARD_REMOVE | TMIO_STAT_CARD_INSERT)
#define TMIO_MASK_IRQ (TMIO_MASK_READOP | TMIO_MASK_WRITEOP | TMIO_MASK_CMD)
+#define TMIO_MIN_DMA_LEN 8
+
#define enable_mmc_irqs(host, i) \
do { \
u32 mask;\
@@ -147,6 +149,7 @@ struct tmio_mmc_host {
struct platform_device *pdev;
/* DMA support */
+ bool force_pio;
struct dma_chan *chan_rx;
struct dma_chan *chan_tx;
struct tasklet_struct dma_complete;
@@ -384,6 +387,7 @@ static void tmio_mmc_reset_work(struct work_struct *work)
host->cmd = NULL;
host->data = NULL;
host->mrq = NULL;
+ host->force_pio = false;
spin_unlock_irqrestore(&host->lock, flags);
@@ -403,6 +407,7 @@ tmio_mmc_finish_request(struct tmio_mmc_host *host)
host->mrq = NULL;
host->cmd = NULL;
host->data = NULL;
+ host->force_pio = false;
cancel_delayed_work(&host->delayed_reset_work);
@@ -484,7 +489,7 @@ static void tmio_mmc_pio_irq(struct tmio_mmc_host *host)
unsigned int count;
unsigned long flags;
- if (host->chan_tx || host->chan_rx) {
+ if ((host->chan_tx || host->chan_rx) && !host->force_pio) {
pr_err("PIO IRQ in DMA mode!\n");
return;
} else if (!data) {
@@ -550,15 +555,11 @@ static void tmio_mmc_do_data_irq(struct tmio_mmc_host *host)
*/
if (data->flags & MMC_DATA_READ) {
- if (!host->chan_rx)
- disable_mmc_irqs(host, TMIO_MASK_READOP);
- else
+ if (host->chan_rx && !host->force_pio)
tmio_check_bounce_buffer(host);
dev_dbg(&host->pdev->dev, "Complete Rx request %p\n",
host->mrq);
} else {
- if (!host->chan_tx)
- disable_mmc_irqs(host, TMIO_MASK_WRITEOP);
dev_dbg(&host->pdev->dev, "Complete Tx request %p\n",
host->mrq);
}
@@ -582,7 +583,7 @@ static void tmio_mmc_data_irq(struct tmio_mmc_host *host)
if (!data)
goto out;
- if (host->chan_tx && (data->flags & MMC_DATA_WRITE)) {
+ if (host->chan_tx && (data->flags & MMC_DATA_WRITE) && !host->force_pio) {
/*
* Has all data been written out yet? Testing on SuperH showed,
* that in most cases the first interrupt comes already with the
@@ -595,11 +596,12 @@ static void tmio_mmc_data_irq(struct tmio_mmc_host *host)
disable_mmc_irqs(host, TMIO_STAT_DATAEND);
tasklet_schedule(&host->dma_complete);
}
- } else if (host->chan_rx && (data->flags & MMC_DATA_READ)) {
+ } else if (host->chan_rx && (data->flags & MMC_DATA_READ) && !host->force_pio) {
disable_mmc_irqs(host, TMIO_STAT_DATAEND);
tasklet_schedule(&host->dma_complete);
} else {
tmio_mmc_do_data_irq(host);
+ disable_mmc_irqs(host, TMIO_MASK_READOP | TMIO_MASK_WRITEOP);
}
out:
spin_unlock(&host->lock);
@@ -648,12 +650,12 @@ static void tmio_mmc_cmd_irq(struct tmio_mmc_host *host,
*/
if (host->data && !cmd->error) {
if (host->data->flags & MMC_DATA_READ) {
- if (!host->chan_rx)
+ if (host->force_pio || !host->chan_rx)
enable_mmc_irqs(host, TMIO_MASK_READOP);
else
tasklet_schedule(&host->dma_issue);
} else {
- if (!host->chan_tx)
+ if (host->force_pio || !host->chan_tx)
enable_mmc_irqs(host, TMIO_MASK_WRITEOP);
else
tasklet_schedule(&host->dma_issue);
@@ -811,6 +813,11 @@ static void tmio_mmc_start_dma_rx(struct tmio_mmc_host *host)
goto pio;
}
+ if (sg->length < TMIO_MIN_DMA_LEN) {
+ host->force_pio = true;
+ return;
+ }
+
disable_mmc_irqs(host, TMIO_STAT_RXRDY);
/* The only sg element can be unaligned, use our bounce buffer then */
@@ -886,6 +893,11 @@ static void tmio_mmc_start_dma_tx(struct tmio_mmc_host *host)
goto pio;
}
+ if (sg->length < TMIO_MIN_DMA_LEN) {
+ host->force_pio = true;
+ return;
+ }
+
disable_mmc_irqs(host, TMIO_STAT_TXRQ);
/* The only sg element can be unaligned, use our bounce buffer then */
@@ -1132,6 +1144,7 @@ static void tmio_mmc_request(struct mmc_host *mmc, struct mmc_request *mrq)
fail:
host->mrq = NULL;
+ host->force_pio = false;
mrq->cmd->error = ret;
mmc_request_done(mmc, mrq);
}
--
1.7.2.3
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