Re: [PATCH v4 2/7] mmc: mediatek: Add Mediatek MMC driver
From: Sascha Hauer
Date: Thu Jun 04 2015 - 05:02:42 EST
On Thu, Jun 04, 2015 at 10:54:03AM +0800, Chaotian Jing wrote:
> 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:
> > > Add Mediatek MMC driver code
> > > Support eMMC/SD/SDIO
> > >
> > > Signed-off-by: Chaotian Jing <chaotian.jing@xxxxxxxxxxxx>
> > > ---
> > > 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 ?
Yes, please.
Sascha
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