Add support for setting a maximum DMA latency via the
PM QOS framework.
Drivers can set host->dma_latency to the desired value
otherwise the initial value (PM_QOS_DEFAULT_VALUE)
will result in no PM QOS request being added.
It may be that there isn't time between consecutive
I/O requests to reach deeper C-states. To address
that the driver can set host->lat_cancel_delay which
is the delay before cancelling the DMA latency request
when it is known that there is another request on
the way.
Signed-off-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>
---
drivers/mmc/host/sdhci.c | 52 ++++++++++++++++++++++++++++++++++++++++++++++++
drivers/mmc/host/sdhci.h | 7 +++++++
2 files changed, 59 insertions(+)
diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index d8be0bf..3a0859b 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -724,6 +724,45 @@ static void sdhci_set_timeout(struct sdhci_host *host, struct mmc_command *cmd)
}
}
+static bool sdhci_pm_qos_use_dma_latency(struct sdhci_host *host)
+{
+ return host->dma_latency != PM_QOS_DEFAULT_VALUE;
+}
+
+static void sdhci_pm_qos_set_dma_latency(struct sdhci_host *host,
+ struct mmc_request *mrq)
+{
+ if (sdhci_pm_qos_use_dma_latency(host) && mrq->data &&
+ (host->flags & (SDHCI_USE_SDMA | SDHCI_USE_ADMA))) {
+ pm_qos_update_request(&host->pm_qos_req, host->dma_latency);
+ host->pm_qos_set = true;
+ }
+}
+
+static void sdhci_pm_qos_unset(struct sdhci_host *host)
+{
+ unsigned int delay;
+
+ if (host->pm_qos_set) {
+ host->pm_qos_set = false;
+ delay = host->consecutive_req ? host->lat_cancel_delay : 0;
+ pm_qos_cancel_request_lazy(&host->pm_qos_req, delay);
+ }
+}
+
+static void sdhci_pm_qos_add(struct sdhci_host *host)
+{
+ if (sdhci_pm_qos_use_dma_latency(host))
+ pm_qos_add_request(&host->pm_qos_req, PM_QOS_CPU_DMA_LATENCY,
+ PM_QOS_DEFAULT_VALUE);
+}
+
+static void sdhci_pm_qos_remove(struct sdhci_host *host)
+{
+ if (pm_qos_request_active(&host->pm_qos_req))
+ pm_qos_remove_request(&host->pm_qos_req);
+}
+
static void sdhci_prepare_data(struct sdhci_host *host, struct mmc_command *cmd)
{
u8 ctrl;
@@ -1348,6 +1387,8 @@ static void sdhci_request(struct mmc_host *mmc, struct mmc_request *mrq)
err = mmc_retune(mmc);
+ sdhci_pm_qos_set_dma_latency(host, mrq);
+
/* Firstly check card presence */
present = sdhci_do_get_cd(host);
@@ -1371,6 +1412,7 @@ static void sdhci_request(struct mmc_host *mmc, struct mmc_request *mrq)
}
host->mrq = mrq;
+ host->consecutive_req = 0;
if (!err && (!present || host->flags & SDHCI_DEVICE_DEAD))
err = -ENOMEDIUM;
@@ -2167,6 +2209,8 @@ static void sdhci_pre_req(struct mmc_host *mmc, struct mmc_request *mrq,
{
struct sdhci_host *host = mmc_priv(mmc);
+ host->consecutive_req = 1;
+
if (mrq->data->host_cookie) {
mrq->data->host_cookie = 0;
return;
@@ -2243,6 +2287,8 @@ static void sdhci_tasklet_finish(unsigned long param)
host = (struct sdhci_host*)param;
+ sdhci_pm_qos_unset(host);
+
spin_lock_irqsave(&host->lock, flags);
/*
@@ -2877,6 +2923,7 @@ struct sdhci_host *sdhci_alloc_host(struct device *dev,
host = mmc_priv(mmc);
host->mmc = mmc;
+ host->dma_latency = PM_QOS_DEFAULT_VALUE;
return host;
}
@@ -3363,6 +3410,8 @@ int sdhci_add_host(struct sdhci_host *host)
*/
mmc->max_blk_count = (host->quirks & SDHCI_QUIRK_NO_MULTIBLOCK) ? 1 : 65535;
+ sdhci_pm_qos_add(host);
+
/*
* Init tasklets.
*/
@@ -3426,6 +3475,7 @@ reset:
#endif
untasklet:
tasklet_kill(&host->finish_tasklet);
+ sdhci_pm_qos_remove(host);
return ret;
}
@@ -3482,6 +3532,8 @@ void sdhci_remove_host(struct sdhci_host *host, int dead)
host->adma_table = NULL;
host->align_buffer = NULL;
+
+ sdhci_pm_qos_remove(host);
}
EXPORT_SYMBOL_GPL(sdhci_remove_host);
diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
index 5521d29..15c5e7b 100644
--- a/drivers/mmc/host/sdhci.h
+++ b/drivers/mmc/host/sdhci.h
@@ -19,6 +19,7 @@
#include <linux/io.h>
#include <linux/mmc/host.h>
+#include <linux/pm_qos.h>
/*
* Controller registers
@@ -419,6 +420,12 @@ struct sdhci_host {
struct mmc_host *mmc; /* MMC structure */
u64 dma_mask; /* custom DMA mask */
+ struct pm_qos_request pm_qos_req;
+ int dma_latency;
+ int lat_cancel_delay;
+ int consecutive_req;
+ bool pm_qos_set;
+
#if defined(CONFIG_LEDS_CLASS) || defined(CONFIG_LEDS_CLASS_MODULE)
struct led_classdev led; /* LED control */
char led_name[32];
--
1.9.1
--
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