linux-kernel - [PATCH] mmc: dw_mmc: rockchip: Don't recalc the clock when it goes off

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Message-Id: <1413304752-7823-1-git-send-email-dianders@chromium.org>
Date:	Tue, 14 Oct 2014 09:39:12 -0700
From:	Doug Anderson <dianders@...omium.org>
To:	Ulf Hansson <ulf.hansson@...aro.org>,
	Seungwon Jeon <tgih.jun@...sung.com>,
	Jaehoon Chung <jh80.chung@...sung.com>
Cc:	Addy Ke <addy.ke@...k-chips.com>,
	Sonny Rao <sonnyrao@...omium.org>,
	Alim Akhtar <alim.akhtar@...sung.com>,
	Andrew Bresticker <abrestic@...omium.org>,
	Doug Anderson <dianders@...omium.org>, heiko@...ech.de,
	chris@...ntf.net, linux-mmc@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-rockchip@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: [PATCH] mmc: dw_mmc: rockchip: Don't recalc the clock when it goes off

The "set_ios" function is called with a clock of 0 when the clock is
turning off.  There's no reason to go through all the extra Rockchip
logic (whose goal is to make sure DIV is 0 or 1) in that case.  The
Rockchip logic happened to work because the CCF will pick the lowest
possible rate when you ask it for a clock of 0, but it's silly to go
through all the remuxing and adjusting for no reason.

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

diff --git a/drivers/mmc/host/dw_mmc-rockchip.c b/drivers/mmc/host/dw_mmc-rockchip.c
index f0c2cb1..bbb4ec3 100644
--- a/drivers/mmc/host/dw_mmc-rockchip.c
+++ b/drivers/mmc/host/dw_mmc-rockchip.c
@@ -37,6 +37,9 @@ static void dw_mci_rk3288_set_ios(struct dw_mci *host, struct mmc_ios *ios)
 	unsigned int cclkin;
 	u32 bus_hz;
 
+	if (ios->clock == 0)
+		return;
+
 	/*
 	 * cclkin: source clock of mmc controller
 	 * bus_hz: card interface clock generated by CLKGEN
-- 
2.1.0.rc2.206.gedb03e5

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