For host controllers using SDHCI_QUIRK_DATA_TIMEOUT_USES_SDCLK, since the card
clock is changed dynamically for different cards, it does not make sense
to use the maximum host clock to calculate max_discard_to which may lead
the max_discard_to to be much smaller than its capbility and affect the card
discard performance a lot.
e.g. the host clock is 200Mhz, but the card is working on 50Mhz. Then the
max_discard_to is only 1/4 of its real capbility.
In this patch, it uses the actual_clock to calculate the max_discard_to
dynamically as long as a new clock speed is set.
Tested with a high speed SDHC card shows:
Originally:
mmc1: new high speed SDHC card at address aaaa
mmc1: calculated max. discard sectors 49152 for timeout 1355 ms
Now:
mmc1: new high speed SDHC card at address aaaa
mmc1: calculated max. discard sectors 712704 for timeout 5422 ms
The max_discard_sectors will increase a lot which will also improve discard
performance a lot.
The one known limitation of this approach is that it does not cover the special
case for user changes the clock via sysfs, since the max_discard_to is only
initialised for one time during the mmc queue init.
Signed-off-by: Dong Aisheng <b29396@xxxxxxxxxxxxx>
---
drivers/mmc/host/sdhci.c | 27 +++++++++++++++++++++------
1 files changed, 21 insertions(+), 6 deletions(-)
diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index 4cc3bd6..9be8a79 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -1143,14 +1143,14 @@ static void sdhci_set_clock(struct sdhci_host *host, unsigned int clock)
unsigned long timeout;
if (clock && clock == host->clock)
- return;
+ goto out;
host->mmc->actual_clock = 0;
if (host->ops->set_clock) {
host->ops->set_clock(host, clock);
if (host->quirks & SDHCI_QUIRK_NONSTANDARD_CLOCK)
- return;
+ goto out;
}
sdhci_writew(host, 0, SDHCI_CLOCK_CONTROL);
@@ -1249,6 +1249,19 @@ clock_set:
out:
host->clock = clock;
+
+ /* update timeout_clk and max_discard_to once the SDCLK is changed */
+ if (host->quirks & SDHCI_QUIRK_DATA_TIMEOUT_USES_SDCLK && clock) {
+ host->timeout_clk = host->mmc->actual_clock ?
+ host->mmc->actual_clock / 1000 :
+ host->clock / 1000;
+ if (host->ops->get_max_timeout)
+ host->mmc->max_discard_to =
+ host->ops->get_max_timeout(host);
+ else
+ host->mmc->max_discard_to = (1 << 27) /
+ host->timeout_clk;
+ }
}
static inline void sdhci_update_clock(struct sdhci_host *host)
@@ -2939,10 +2952,12 @@ int sdhci_add_host(struct sdhci_host *host)
if (host->quirks & SDHCI_QUIRK_DATA_TIMEOUT_USES_SDCLK)
host->timeout_clk = mmc->f_max / 1000;
- if (host->ops->get_max_timeout)
- mmc->max_discard_to = host->ops->get_max_timeout(host);
- else
- mmc->max_discard_to = (1 << 27) / host->timeout_clk;
+ if (!(host->quirks & SDHCI_QUIRK_DATA_TIMEOUT_USES_SDCLK)) {
+ if (host->ops->get_max_timeout)
+ mmc->max_discard_to = host->ops->get_max_timeout(host);
+ else
+ mmc->max_discard_to = (1 << 27) / host->timeout_clk;
+ }
mmc->caps |= MMC_CAP_SDIO_IRQ | MMC_CAP_ERASE | MMC_CAP_CMD23;
--
1.7.2.rc3
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