[PATCH] mmc: print debug messages for runtime PM actions

[PATCH] mmc: print debug messages for runtime PM actions

[Daniel Drake]

At
http://www.mail-archive.com/linux-mmc@vger.kernel.org/msg08371.html
we found and fixed a bug where mmc's runtime power management functions
were not being called. We have now also made improvements to the SDIO
powerup routine which could possibly mask this kind of issue in future.

Add debug messages to the runtime PM hooks so that it is easy to verify
if and when runtime PM is happening.

Signed-off-by: Daniel Drake <dsd@laptop.org>
---
 drivers/mmc/core/core.c |    8 ++++++++
 1 files changed, 8 insertions(+), 0 deletions(-)

For linux-3.1.

diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index 0a04886..ad0c55a 100644
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -1664,6 +1664,10 @@ int mmc_power_save_host(struct mmc_host *host)
 {
 	int ret = 0;
 
+#ifdef CONFIG_MMC_DEBUG
+	pr_info("%s: %s: powering down\n", mmc_hostname(host), __func__);
+#endif
+
 	mmc_bus_get(host);
 
 	if (!host->bus_ops || host->bus_dead || !host->bus_ops->power_restore) {
@@ -1686,6 +1690,10 @@ int mmc_power_restore_host(struct mmc_host *host)
 {
 	int ret;
 
+#ifdef CONFIG_MMC_DEBUG
+	pr_info("%s: %s: powering up\n", mmc_hostname(host), __func__);
+#endif
+
 	mmc_bus_get(host);
 
 	if (!host->bus_ops || host->bus_dead || !host->bus_ops->power_restore) {
-- 
1.7.6

Re: [PATCH] mmc: print debug messages for runtime PM actions

[Chris Ball]

Hi Dan,

On Sun, Jul 17 2011, Daniel Drake wrote:
> At
> http://www.mail-archive.com/linux-mmc@vger.kernel.org/msg08371.html
> we found and fixed a bug where mmc's runtime power management functions
> were not being called. We have now also made improvements to the SDIO
> powerup routine which could possibly mask this kind of issue in future.
>
> Add debug messages to the runtime PM hooks so that it is easy to verify
> if and when runtime PM is happening.
>
> Signed-off-by: Daniel Drake <dsd@laptop.org>
> ---
>  drivers/mmc/core/core.c |    8 ++++++++
>  1 files changed, 8 insertions(+), 0 deletions(-)
>
> For linux-3.1.
>
> diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
> index 0a04886..ad0c55a 100644
> --- a/drivers/mmc/core/core.c
> +++ b/drivers/mmc/core/core.c
> @@ -1664,6 +1664,10 @@ int mmc_power_save_host(struct mmc_host *host)
>  {
>  	int ret = 0;
>  
> +#ifdef CONFIG_MMC_DEBUG
> +	pr_info("%s: %s: powering down\n", mmc_hostname(host), __func__);
> +#endif
> +

Did you consider just:

	pr_debug("%s: %s: powering down\n", mmc_hostname(host), __func__);

which gets you the same CONFIG_MMC_DEBUG semantics?  (The messages will
be at the debug loglevel rather than info, but that sounds right to me.)

Thanks,

- Chris.
-- 
Chris Ball   <cjb@laptop.org>   <http://printf.net/>
One Laptop Per Child

Re: [PATCH] mmc: print debug messages for runtime PM actions

[Daniel Drake]

On 19 July 2011 03:31, Chris Ball <cjb@laptop.org> wrote:
> Did you consider just:
>
>        pr_debug("%s: %s: powering down\n", mmc_hostname(host), __func__);
>
> which gets you the same CONFIG_MMC_DEBUG semantics?  (The messages will
> be at the debug loglevel rather than info, but that sounds right to me.)

I did, and that would probably be fine (assuming that CONFIG_MMC_DEBUG
would actually turn it on? I can't see where that would happen), but I
was trying to make it a bit more prominent and appear the same as the
debug message from mmc_rescan_try_freq() which does it in this way.

Daniel

Re: [PATCH] mmc: print debug messages for runtime PM actions

[Chris Ball]

Hi,

On Wed, Jul 20 2011, Daniel Drake wrote:
>>     pr_debug("%s: %s: powering down\n", mmc_hostname(host), __func__);
>>
>> which gets you the same CONFIG_MMC_DEBUG semantics? (The messages will
>> be at the debug loglevel rather than info, but that sounds right to me.)
>
> I did, and that would probably be fine (assuming that CONFIG_MMC_DEBUG
> would actually turn it on? I can't see where that would happen)

It's in drivers/mmc/Makefile:
subdir-ccflags-$(CONFIG_MMC_DEBUG) := -DDEBUG

include/linux/printk.h:
#if defined(DEBUG)
#define pr_debug(fmt, ...) \
        printk(KERN_DEBUG pr_fmt(fmt), ##__VA_ARGS__)
        
> was trying to make it a bit more prominent and appear the same as the
> debug message from mmc_rescan_try_freq() which does it in this way.

Ah, okay, seems reasonable -- I'll merge the original patch for 3.1.

Thanks!

- Chris.
-- 
Chris Ball   <cjb@laptop.org>   <http://printf.net/>
One Laptop Per Child