On Tue, 2015-05-19 at 13:15 +0200, Sascha Hauer wrote:

On Tue, May 19, 2015 at 02:36:46PM +0800, Chaotian Jing wrote:

quoted

Add Mediatek MMC driver code
Support eMMC/SD/SDIO

Signed-off-by: Chaotian Jing <chaotian.jing@mediatek.com>
---
 drivers/mmc/host/Kconfig  |    8 +
 drivers/mmc/host/Makefile |    1 +
 drivers/mmc/host/mtk-sd.c | 1422 +++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 1431 insertions(+)
 create mode 100644 drivers/mmc/host/mtk-sd.c

+
+	host->src_clk = devm_clk_get(&pdev->dev, "source");
+	if (IS_ERR(host->src_clk)) {
+		ret = PTR_ERR(host->src_clk);
+		goto host_free;
+	}
+
+	host->h_clk = devm_clk_get(&pdev->dev, "hclk");
+	if (IS_ERR(host->h_clk)) {
+		/* host->h_clk is optional, Only for MSDC0/3 at MT8173 */
+		dev_dbg(&pdev->dev,
+				"Invalied hclk from the device tree!\n");
+	}

s/Invalied/Invalid/

According to my reference manual the controller always needs a hclk. It
seems on some controllers it is just not software controllable. If
that's the case you should always provide a hclk to the driver and make
this clock mandatory.

For MT8173, MSDC1, MSDC2's HCLK are in Infra, software cannot control
it. So just set the HCLK to clk_null ?

If it is, will set HCLK to clk_null at next revision, and the same
changes will make for MT8135.

Sascha