Hi Jaehoon/Adrian,
On Thu, Sep 16, 2010 at 03:46:50PM +0900, Jaehoon Chung wrote:
> Hi all,
> This is a RFC patch that support clock-gating for saving power consumption.
> I found mmc_host_enable/mmc_host_disable function in core.c
> (using MMC_CAP_DSIABLE. i think that use when host enable/disable)
> So, i used that functions and implemented some functions in sdhci-s3c.c & sdhci.c
>
> i want any feedback. how do you think about this patch?
> Plz let me know...
A few points:
* Have you tested this patch? Did you see a decrease in power
consumption? How large was the decrease?
* I don't understand exactly how/when you're expecting to save power
with this approach of defining .{enable,disable}() without then
calling them from your driver code. Under which circumstances do
you think this will power down the clock?
* CC'ing Adrian for help with review, since he wrote these callbacks.
Thanks,
- Chris.
> Thank you all
>
> Signed-off-by: Jaehoon Chung <jh80.chung@xxxxxxxxxxx>
> Signed-off-by: Kyungmin Park <kyungmin.park@xxxxxxxxxxx>
>
> ---
> drivers/mmc/host/sdhci-s3c.c | 36 ++++++++++++++++++++++++++++++++++++
> drivers/mmc/host/sdhci.c | 30 ++++++++++++++++++++++++++++++
> drivers/mmc/host/sdhci.h | 4 ++++
> 3 files changed, 70 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/mmc/host/sdhci-s3c.c b/drivers/mmc/host/sdhci-s3c.c
> index 71ad416..9b430fb 100644
> --- a/drivers/mmc/host/sdhci-s3c.c
> +++ b/drivers/mmc/host/sdhci-s3c.c
> @@ -47,6 +47,7 @@ struct sdhci_s3c {
> unsigned int cur_clk;
> int ext_cd_irq;
> int ext_cd_gpio;
> + int flag;
>
> struct clk *clk_io;
> struct clk *clk_bus[MAX_BUS_CLK];
> @@ -232,10 +233,45 @@ static unsigned int sdhci_s3c_get_min_clock(struct sdhci_host *host)
> return min;
> }
>
> +static int sdhci_s3c_enable_clk(struct sdhci_host *host)
> +{
> + struct sdhci_s3c *sc = to_s3c(host);
> +
> + if (sc->flag != 1) {
> + clk_disable(sc->clk_io);
> + clk_disable(sc->clk_bus[sc->cur_clk]);
> + }
> +
> + if (sc->host->clk_cnt == 0) {
> + clk_enable(sc->clk_io);
> + clk_enable(sc->clk_bus[sc->cur_clk]);
> + sc->host->clk_cnt++;
> + sc->flag = 1;
> + }
> +
> + return 0;
> +}
> +
> +static int sdhci_s3c_disable_clk(struct sdhci_host *host, int lazy)
> +{
> + struct sdhci_s3c *sc = to_s3c(host);
> +
> + if (sc->host->clk_cnt) {
> + clk_disable(sc->clk_io);
> + clk_disable(sc->clk_bus[sc->cur_clk]);
> + if (sc->host->clk_cnt)
> + sc->host->clk_cnt--;
> + }
> +
> + return 0;
> +}
> +
> static struct sdhci_ops sdhci_s3c_ops = {
> .get_max_clock = sdhci_s3c_get_max_clk,
> .set_clock = sdhci_s3c_set_clock,
> .get_min_clock = sdhci_s3c_get_min_clock,
> + .enable = sdhci_s3c_enable_clk,
> + .disable = sdhci_s3c_disable_clk,
> };
>
> static void sdhci_s3c_notify_change(struct platform_device *dev, int state)
> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
> index 401527d..fa2e55d 100644
> --- a/drivers/mmc/host/sdhci.c
> +++ b/drivers/mmc/host/sdhci.c
> @@ -1245,7 +1245,37 @@ out:
> spin_unlock_irqrestore(&host->lock, flags);
> }
>
> +static int sdhci_enable_clk(struct mmc_host *mmc)
> +{
> + struct sdhci_host *host = mmc_priv(mmc);
> + int ret = 0;
> +
> + if (host->old_clock != 0 && host->clock == 0) {
> + if (host->ops->enable)
> + ret = host->ops->enable(host);
> + sdhci_set_clock(host, host->old_clock);
> + }
> +
> + return ret;
> +}
> +
> +static int sdhci_disable_clk(struct mmc_host *mmc, int lazy)
> +{
> + struct sdhci_host *host = mmc_priv(mmc);
> + int ret = 0;
> +
> + if (host->clock != 0) {
> + host->old_clock = host->clock;
> + sdhci_set_clock(host, 0);
> + if (host->ops->disable)
> + ret = host->ops->disable(host, lazy);
> + }
> + return ret;
> +}
> +
> static const struct mmc_host_ops sdhci_ops = {
> + .enable = sdhci_enable_clk,
> + .disable = sdhci_disable_clk,
> .request = sdhci_request,
> .set_ios = sdhci_set_ios,
> .get_ro = sdhci_get_ro,
> diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
> index d316bc7..0c6f143 100644
> --- a/drivers/mmc/host/sdhci.h
> +++ b/drivers/mmc/host/sdhci.h
> @@ -278,6 +278,8 @@ struct sdhci_host {
> unsigned int timeout_clk; /* Timeout freq (KHz) */
>
> unsigned int clock; /* Current clock (MHz) */
> + unsigned int old_clock; /* Old clock (MHz) */
> + unsigned int clk_cnt; /* Clock user count */
> u8 pwr; /* Current voltage */
>
> struct mmc_request *mrq; /* Current request */
> @@ -323,6 +325,8 @@ struct sdhci_ops {
> unsigned int (*get_max_clock)(struct sdhci_host *host);
> unsigned int (*get_min_clock)(struct sdhci_host *host);
> unsigned int (*get_timeout_clock)(struct sdhci_host *host);
> + int (*enable)(struct sdhci_host *host);
> + int (*disable)(struct sdhci_host *host, int lazy);
> };
>
> #ifdef CONFIG_MMC_SDHCI_IO_ACCESSORS
> -- 1.6.0.4
--
Chris Ball <cjb@xxxxxxxxxx> <http://printf.net/>
One Laptop Per Child
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