linux-kernel - [PATCH 4/5] mmc: dw_mmc: Always setup the bus after suspend/resume

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Message-Id: <1373391071-6312-5-git-send-email-dianders@chromium.org>
Date:	Tue,  9 Jul 2013 10:31:10 -0700
From:	Doug Anderson <dianders@...omium.org>
To:	Chris Ball <cjb@...top.org>
Cc:	Olof Johansson <olof@...om.net>,
	Jaehoon Chung <jh80.chung@...sung.com>,
	Seungwon Jeon <tgih.jun@...sung.com>,
	James Hogan <james.hogan@...tec.com>,
	Grant Grundler <grundler@...omium.org>,
	Alim Akhtar <alim.akhtar@...sung.com>,
	Abhilash Kesavan <a.kesavan@...sung.com>,
	Tomasz Figa <tomasz.figa@...il.com>,
	Doug Anderson <dianders@...omium.org>,
	linux-mmc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 4/5] mmc: dw_mmc: Always setup the bus after suspend/resume

After suspend/resume all of the dw_mmc registers are reset to
defaults.  We restore most of them, but specifically don't setup the
clock registers after resume unless we've got a powered card.  Things
still work because the core will eventually call set_ios() and we'll
set things up.

There doesn't seem to be any reason that I can see _not_ to set things
up after resume.  Restoring this state makes the code easier to reason
about and should help prevent bugs.  It also allows us to do a
register dump before and after suspend/resume to confirm that we've
set things up OK.

I examined the state of the dw_mmc instance before and after suspend
after this patch.  I had no card inserted in an SD card slot.

Before this patch, differences were:
* CLKDIV (0x08)
* CLKENA (0x10)
* TMOUT (0x14)
* CMD (0x2C) - difference is not important
* CLKSEL (0x9C - exynos specific)

After this patch, only TMOUT was different.  I have a separate patch
for that.

Signed-off-by: Doug Anderson <dianders@...omium.org>
---
 drivers/mmc/host/dw_mmc.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
index 2aaa93f..a0a07df 100644
--- a/drivers/mmc/host/dw_mmc.c
+++ b/drivers/mmc/host/dw_mmc.c
@@ -2510,9 +2510,7 @@ int dw_mci_resume(struct dw_mci *host)
 		struct dw_mci_slot *slot = host->slot[i];
 		if (!slot)
 			continue;
-		if (slot->mmc->pm_flags & MMC_PM_KEEP_POWER) {
-			dw_mci_set_ios(slot->mmc, &slot->mmc->ios);
-		}
+		dw_mci_set_ios(slot->mmc, &slot->mmc->ios);

 		ret = mmc_resume_host(host->slot[i]->mmc);
 		if (ret < 0)
-- 
1.8.3

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