[PATCH 07/11] sdhci: Add quirk to suppress PIO interrupts during DMA transfers

Anton Vorontsov
2009-02-06T18:09:12Z

Some hosts (that is, FSL eSDHC) throw PIO interrupts during DMA
transfers, this causes tons of unneeded interrupts, and thus highly
degraded speed.

This patch adds SDHCI_QUIRK_PIO_IRQS_DURING_DMA quirk. When specified,
the sdhci driver will disable PIO interrupts during DMA transfers.

Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
---
drivers/mmc/host/sdhci.c | 32 ++++++++++++++++++++++++++++++++
drivers/mmc/host/sdhci.h | 3 +++
2 files changed, 35 insertions(+), 0 deletions(-)

diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index 9b43588..ede3790 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -167,6 +167,8 @@ static void sdhci_init(struct sdhci_host *host)

sdhci_writel(host, intmask, SDHCI_INT_ENABLE);
sdhci_writel(host, intmask, SDHCI_SIGNAL_ENABLE);
+
+ host->flags &= ~SDHCI_PIO_DISABLED;
}

static void sdhci_activate_led(struct sdhci_host *host)
@@ -594,6 +596,33 @@ static u8 sdhci_calc_timeout(struct sdhci_host *host, struct mmc_data *data)
return count;
}

+static void sdhci_set_pio_irqs(struct sdhci_host *host, bool state)
+{
+ bool current_state = !(host->flags & SDHCI_PIO_DISABLED);
+ u32 ier;
+
+ /*
+ * We only care about PIO IRQs if the host issues PIO IRQs during
+ * DMA transfers. Otherwise we can keep the irqs always enabled.
+ */
+ if (!(host->quirks & SDHCI_QUIRK_PIO_IRQS_DURING_DMA))
+ return;
+
+ if (current_state == state)
+ return;
+
+ ier = sdhci_readl(host, SDHCI_INT_ENABLE);
+ if (state) {
+ ier |= SDHCI_INT_DATA_AVAIL | SDHCI_INT_SPACE_AVAIL;
+ host->flags &= ~SDHCI_PIO_DISABLED;
+ } else {
+ ier &= ~(SDHCI_INT_DATA_AVAIL | SDHCI_INT_SPACE_AVAIL);
+ host->flags |= SDHCI_PIO_DISABLED;
+ }
+ sdhci_writel(host, ier, SDHCI_INT_ENABLE);
+ sdhci_writel(host, ier, SDHCI_SIGNAL_ENABLE);
+}
+
static void sdhci_prepare_data(struct sdhci_host *host, struct mmc_data *data)
{
u8 count;
@@ -740,6 +769,9 @@ static void sdhci_prepare_data(struct sdhci_host *host, struct mmc_data *data)
sg_miter_start(&host->sg_miter,
data->sg, data->sg_len, SG_MITER_ATOMIC);
host->blocks = data->blocks;
+ sdhci_set_pio_irqs(host, true);
+ } else {
+ sdhci_set_pio_irqs(host, false);
}

/* We do not handle DMA boundaries, so set it to max (512 KiB) */
diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
index c4edd52..2e8dfd1 100644
--- a/drivers/mmc/host/sdhci.h
+++ b/drivers/mmc/host/sdhci.h
@@ -235,6 +235,8 @@ struct sdhci_host {
#define SDHCI_QUIRK_INVERTED_WRITE_PROTECT (1<<17)
/* Controller has all registers of 32 bit width */
#define SDHCI_QUIRK_32BIT_REGISTERS (1<<18)
+/* Controller issues PIO interrupts during DMA transfers */
+#define SDHCI_QUIRK_PIO_IRQS_DURING_DMA (1<<19)

int irq; /* Device IRQ */
void __iomem * ioaddr; /* Mapped address */
@@ -256,6 +258,7 @@ struct sdhci_host {
#define SDHCI_USE_ADMA (1<<1) /* Host is ADMA capable */
#define SDHCI_REQ_USE_DMA (1<<2) /* Use DMA for this req. */
#define SDHCI_DEVICE_DEAD (1<<3) /* Device unresponsive */
+#define SDHCI_PIO_DISABLED (1<<4) /* PIO IRQs disabled */

unsigned int version; /* SDHCI spec. version */

--
1.5.6.5