Re: [PATCH V2] mmc: core: Add option to prevent eMMC sleep command

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Subhash Jadavani wrote:
  On 12/19/2011 4:42 PM, Ulf Hansson wrote:
Subhash Jadavani wrote:
-----Original Message-----
From: linux-mmc-owner@xxxxxxxxxxxxxxx [mailto:linux-mmc-
owner@xxxxxxxxxxxxxxx] On Behalf Of Ulf Hansson
Sent: Thursday, December 15, 2011 3:06 PM
To: linux-mmc@xxxxxxxxxxxxxxx; Chris Ball
Cc: Per Forlin; Ulf Hansson; Johan Rudholm; Lee Jones
Subject: [PATCH V2] mmc: core: Add option to prevent eMMC sleep command

Host may now use MMC_CAP2_NOSLEEP to disable the use of
eMMC sleep/awake command.

This option can be used when you platform have a buggy
kernel crash dump software, which is supposed to store
the dump on the eMMC, but is not able to wake up the eMMC
from sleep state.

Signed-off-by: Ulf Hansson <ulf.hansson@xxxxxxxxxxxxxx>
Reviewed-by: Hanumath Prasad <hanumath.prasad@xxxxxxxxxxxxxx>
Reviewed-by: Srinidhi Kasagar <srinidhi.kasagar@xxxxxxxxxxxxxx>
---

Changes in v2:
    - Added some motivation to why this patch is wanted in the
    commit message.

---
 drivers/mmc/core/core.c  |    6 ++++++
 include/linux/mmc/host.h |    1 +
 2 files changed, 7 insertions(+), 0 deletions(-)

diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index a2aa860..5a1ce37 100644
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -2246,6 +2246,9 @@ int mmc_card_awake(struct mmc_host *host)
 {
     int err = -ENOSYS;

+    if (host->caps2 & MMC_CAP2_NOSLEEP)
+        return 0;
+
     mmc_bus_get(host);

     if (host->bus_ops && !host->bus_dead && host->bus_ops->awake)
@@ -2261,6 +2264,9 @@ int mmc_card_sleep(struct mmc_host *host)
 {
     int err = -ENOSYS;

+    if (host->caps2 & MMC_CAP2_NOSLEEP)
+        return 0;
+
     mmc_bus_get(host);

     if (host->bus_ops && !host->bus_dead && host->bus_ops->sleep)
diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
index 9a03d03..d07fb27 100644
--- a/include/linux/mmc/host.h
+++ b/include/linux/mmc/host.h
@@ -242,6 +242,7 @@ struct mmc_host {
 #define MMC_CAP2_CACHE_CTRL    (1 << 1)    /* Allow cache control */
 #define MMC_CAP2_POWEROFF_NOTIFY (1 << 2)    /* Notify poweroff
supported */
 #define MMC_CAP2_NO_MULTI_READ    (1 << 3)    /* Multiblock reads
don't work */
+#define MMC_CAP2_NOSLEEP    (1 << 4)    /* Don't allow sleep command
Can we rename this CAP to something like "MMC_CAP2_NO_MMC_SLEEP_CMD" to make
it more specific?

The "cap" actually disables the execution of the mmc_card_awake|sleep functions which is not (e)MMC specific functions.

I could change to someting like with *SLEEP_CMD but without *MMC* if that sounds better?
Yes, it sounds good.

OK, fixed in v3 patch. May I add your Ack as well?

Br
Ulf Hansson
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