Re: [linux-sunxi] Re: [PATCH resend 1/3] mmc: sunxi: fix timeout in sunxi_mmc_oclk_onoff

From: Olliver Schinagl
Date: Wed Aug 12 2015 - 08:41:01 EST

While I can't speak for Michal obviously,

I left the debugging bit (in my v2 that i sent 2 minutes ago) as both you and Hans where content with it back then and both acked it.

Michal, feel free to send the v3 without the debug info, unless you want me to do it ;)


On 12-08-15 14:32, Hans de Goede wrote:

On 12-08-15 14:23, michal.suchanek@xxxxxxxxxxx wrote:
The 250ms timeout is too short.

On my system enabling the oclk takes under 50ms and disabling slightly
over 100ms when idle. Under load disabling the clock can take over

This does not make mmc clock gating look like good option to have on
sunxi but the system should not crash with mmc clock gating enabled

This patch sets the timeout to 750ms and adds debug prints which show
how long enabling/disabling the clock took so more data can be collected
from other systems.

Signed-off-by: Michal Suchanek <hramrach@xxxxxxxxx>

This is a big patch for just changing a timeout, most of this is in
extra verbosity which IMHO has little value, in the error path w
know we will have waited aprox 750 ms, so printing the waiting
time there is not worth all the extra code.

As for adding the warning I'm even less of a big fan of that,
if we need higher timeouts, we need higher timeouts, spamming the
kernel logs with that we are actually hitting the higher timeouts
is not productive IMHO.

Can you please resend this as a one-liner just changing the timeout ?




- fix formatting
drivers/mmc/host/sunxi-mmc.c | 22 +++++++++++++++++++---
1 file changed, 19 insertions(+), 3 deletions(-)

diff --git a/drivers/mmc/host/sunxi-mmc.c b/drivers/mmc/host/sunxi-mmc.c
index 4d3e1ff..f808a02 100644
--- a/drivers/mmc/host/sunxi-mmc.c
+++ b/drivers/mmc/host/sunxi-mmc.c
@@ -595,7 +595,7 @@ static irqreturn_t sunxi_mmc_handle_manual_stop(int irq, void *dev_id)

static int sunxi_mmc_oclk_onoff(struct sunxi_mmc_host *host, u32 oclk_en)
- unsigned long expire = jiffies + msecs_to_jiffies(250);
+ unsigned long start, end;
u32 rval;

rval = mmc_readl(host, REG_CLKCR);
@@ -604,6 +604,8 @@ static int sunxi_mmc_oclk_onoff(struct sunxi_mmc_host *host, u32 oclk_en)
if (oclk_en)

+ start = jiffies;
+ end = start + msecs_to_jiffies(750);
mmc_writel(host, REG_CLKCR, rval);

@@ -611,15 +613,29 @@ static int sunxi_mmc_oclk_onoff(struct sunxi_mmc_host *host, u32 oclk_en)

do {
rval = mmc_readl(host, REG_CMDR);
- } while (time_before(jiffies, expire) && (rval & SDXC_START));
+ } while (time_before(jiffies, end) && (rval & SDXC_START));
+ end = jiffies;

/* clear irq status bits set by the command */
mmc_writel(host, REG_RINTR,
mmc_readl(host, REG_RINTR) & ~SDXC_SDIO_INTERRUPT);

if (rval & SDXC_START) {
- dev_err(mmc_dev(host->mmc), "fatal err update clk timeout\n");
+ dev_err(mmc_dev(host->mmc),
+ "fatal err update oclk timeout. Could not %s in %ims.\n",
+ oclk_en ? "enable" : "disable",
+ jiffies_to_msecs(end - start));
return -EIO;
+ } else {
+ int msecs = jiffies_to_msecs(end - start);
+ const char *ing = oclk_en ? "enabling" : "disabling";
+ if ((msecs > 150) || (oclk_en && (msecs > 50)))
+ dev_warn(mmc_dev(host->mmc),
+ "%s oclk took %ims", ing, msecs);
+ else
+ dev_dbg(mmc_dev(host->mmc),
+ "%s oclk took %ims", ing, msecs);

return 0;

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