In the current kernel, the poll interval for the broken CD is hard
coded to 1 second. This will trigger about 50 mmc interrupts per
second on a SoC like fsl p2020 if there is no card in the slot.
The overhead for this is not trivial. So add a module parameter to
make the poll interval adjustable. At the same time make the default
value a bit bigger, and the system which really need the per second
poll can tweak this parameter to be compatible with the old kernel.
Signed-off-by: Kevin Hao <haokexin@xxxxxxxxx>
---
drivers/mmc/core/core.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index 0dc64e6e00d4..b95da0719fb0 100644
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -66,6 +66,10 @@ static const unsigned freqs[] = { 400000, 300000, 200000, 100000 };
bool use_spi_crc = 1;
module_param(use_spi_crc, bool, 0);
+static int rescan_interval = 5;
+module_param(rescan_interval, int, S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);
+MODULE_PARM_DESC(rescan_interval, "Set the poll interval(in seconds) for broken CD(default:5, disable: <=0)");
+
/*
* Internal function. Schedule delayed work in the MMC work queue.
*/
@@ -2507,8 +2511,8 @@ void mmc_rescan(struct work_struct *work)
mmc_release_host(host);
out:
- if (host->caps & MMC_CAP_NEEDS_POLL)
- mmc_schedule_delayed_work(&host->detect, HZ);
+ if ((host->caps & MMC_CAP_NEEDS_POLL) && (rescan_interval > 0))
+ mmc_schedule_delayed_work(&host->detect, HZ * rescan_interval);
}
void mmc_start_host(struct mmc_host *host)
--
1.9.3
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