Question about commit "mmc: core: Support aggressive power management for (e)MMC/SD"

Question about commit "mmc: core: Support aggressive power management for (e)MMC/SD"

[Axel Lin]

Hi Ulf,

While reading the code, I don't figure out why we need a nested mmc_claim_host
/mmc_release_host calls and additional mmc_power_off/mmc_power_up calls in
commit c4d770d72.

The implementation of mmc_suspend/mmc_resume and mmc_sd_suspend/mmc_sd_resume
already calls mmc_claim_host/mmc_release_host and mmc_power_off/mmc_power_up.

I don't have a hardware handy to test it at this moment.
I'm wondering if it still works with below diff:

diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
index 6d02012..f0dcc53 100644
--- a/drivers/mmc/core/mmc.c
+++ b/drivers/mmc/core/mmc.c
@@ -1552,18 +1552,11 @@ static int mmc_runtime_suspend(struct mmc_host *host)
 	if (!(host->caps & MMC_CAP_AGGRESSIVE_PM))
 		return 0;
 
-	mmc_claim_host(host);
-
 	err = mmc_suspend(host);
-	if (err) {
+	if (err)
 		pr_err("%s: error %d doing aggessive suspend\n",
 			mmc_hostname(host), err);
-		goto out;
-	}
-	mmc_power_off(host);
 
-out:
-	mmc_release_host(host);
 	return err;
 }
 
@@ -1577,15 +1570,11 @@ static int mmc_runtime_resume(struct mmc_host *host)
 	if (!(host->caps & MMC_CAP_AGGRESSIVE_PM))
 		return 0;
 
-	mmc_claim_host(host);
-
-	mmc_power_up(host);
 	err = mmc_resume(host);
 	if (err)
 		pr_err("%s: error %d doing aggessive resume\n",
 			mmc_hostname(host), err);
 
-	mmc_release_host(host);
 	return 0;
 }
 
diff --git a/drivers/mmc/core/sd.c b/drivers/mmc/core/sd.c
index 5e8823d..0f2a1f9 100644
--- a/drivers/mmc/core/sd.c
+++ b/drivers/mmc/core/sd.c
@@ -1117,18 +1117,11 @@ static int mmc_sd_runtime_suspend(struct mmc_host *host)
 	if (!(host->caps & MMC_CAP_AGGRESSIVE_PM))
 		return 0;
 
-	mmc_claim_host(host);
-
 	err = mmc_sd_suspend(host);
-	if (err) {
+	if (err)
 		pr_err("%s: error %d doing aggessive suspend\n",
 			mmc_hostname(host), err);
-		goto out;
-	}
-	mmc_power_off(host);
 
-out:
-	mmc_release_host(host);
 	return err;
 }
 
@@ -1142,15 +1135,11 @@ static int mmc_sd_runtime_resume(struct mmc_host *host)
 	if (!(host->caps & MMC_CAP_AGGRESSIVE_PM))
 		return 0;
 
-	mmc_claim_host(host);
-
-	mmc_power_up(host);
 	err = mmc_sd_resume(host);
 	if (err)
 		pr_err("%s: error %d doing aggessive resume\n",
 			mmc_hostname(host), err);
 
-	mmc_release_host(host);
 	return 0;
 }
 

Re: Question about commit "mmc: core: Support aggressive power management for (e)MMC/SD"

[Ulf Hansson]

Axel Lin <axel.lin@ingics.com> skrev:
>Hi Ulf,
>
>While reading the code, I don't figure out why we need a nested
>mmc_claim_host
>/mmc_release_host calls and additional mmc_power_off/mmc_power_up calls
>in
>commit c4d770d72.

Hi Axel,

Please have a look at a patch I sent 3 October. "mmc: core: Remove redundant mmc_power_.....

You have spotted that this code is not needed, I believe the commitmsg in the patch above will give you some background, to why it looked like it did.

Kind regards
Ulf Hansson

>
>The implementation of mmc_suspend/mmc_resume and
>mmc_sd_suspend/mmc_sd_resume
>already calls mmc_claim_host/mmc_release_host and
>mmc_power_off/mmc_power_up.
>
>I don't have a hardware handy to test it at this moment.
>I'm wondering if it still works with below diff:
>
>diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
>index 6d02012..f0dcc53 100644
>--- a/drivers/mmc/core/mmc.c
>+++ b/drivers/mmc/core/mmc.c
>@@ -1552,18 +1552,11 @@ static int mmc_runtime_suspend(struct mmc_host
>*host)
> 	if (!(host->caps & MMC_CAP_AGGRESSIVE_PM))
> 		return 0;
> 
>-	mmc_claim_host(host);
>-
> 	err = mmc_suspend(host);
>-	if (err) {
>+	if (err)
> 		pr_err("%s: error %d doing aggessive suspend\n",
> 			mmc_hostname(host), err);
>-		goto out;
>-	}
>-	mmc_power_off(host);
> 
>-out:
>-	mmc_release_host(host);
> 	return err;
> }
> 
>@@ -1577,15 +1570,11 @@ static int mmc_runtime_resume(struct mmc_host
>*host)
> 	if (!(host->caps & MMC_CAP_AGGRESSIVE_PM))
> 		return 0;
> 
>-	mmc_claim_host(host);
>-
>-	mmc_power_up(host);
> 	err = mmc_resume(host);
> 	if (err)
> 		pr_err("%s: error %d doing aggessive resume\n",
> 			mmc_hostname(host), err);
> 
>-	mmc_release_host(host);
> 	return 0;
> }
> 
>diff --git a/drivers/mmc/core/sd.c b/drivers/mmc/core/sd.c
>index 5e8823d..0f2a1f9 100644
>--- a/drivers/mmc/core/sd.c
>+++ b/drivers/mmc/core/sd.c
>@@ -1117,18 +1117,11 @@ static int mmc_sd_runtime_suspend(struct
>mmc_host *host)
> 	if (!(host->caps & MMC_CAP_AGGRESSIVE_PM))
> 		return 0;
> 
>-	mmc_claim_host(host);
>-
> 	err = mmc_sd_suspend(host);
>-	if (err) {
>+	if (err)
> 		pr_err("%s: error %d doing aggessive suspend\n",
> 			mmc_hostname(host), err);
>-		goto out;
>-	}
>-	mmc_power_off(host);
> 
>-out:
>-	mmc_release_host(host);
> 	return err;
> }
> 
>@@ -1142,15 +1135,11 @@ static int mmc_sd_runtime_resume(struct
>mmc_host *host)
> 	if (!(host->caps & MMC_CAP_AGGRESSIVE_PM))
> 		return 0;
> 
>-	mmc_claim_host(host);
>-
>-	mmc_power_up(host);
> 	err = mmc_sd_resume(host);
> 	if (err)
> 		pr_err("%s: error %d doing aggessive resume\n",
> 			mmc_hostname(host), err);
> 
>-	mmc_release_host(host);
> 	return 0;
> }
>