Hi Girish,
On Thu, Sep 22 2011, Girish K S wrote:
> This patch adds the power class selection feature available
> for mmc versions 4.0 and above.
> During the enumeration stage before switching to the lower
> data bus, check if the power class is supported for the
> current bus width. If the power class is available then
> switch to the power class and use the higher data bus. If
> power class is not supported then switch to the lower data
> bus in a worst case.
>
> Signed-off-by: Girish K S
> ---
> v1:
> This patch version modifies the power_class_select function prototype.
> During device enumeration, when the host tries to read the extended
> csd register after switching to higher bus width, the read fails at
> higher bus width. So the power_class_select function is modified to
> reuse the extended csd register values read with 1 bit bus width.
> v2:
> This patch version removes some checkpatch error
> v3:
> updated with review comments made by chris ball. patch generated
> by rebasing to chris balls mmc-next branch.
The mmc.h patch doesn't apply against today's mmc-next branch -- maybe
due to a patch I pushed yesterday, also make sure that you're on the
mmc-next branch, not master. Mind rebasing once more, please? And:
> drivers/mmc/core/mmc.c | 91
> +++
> include/linux/mmc/mmc.h | 13 +++
> 2 files changed, 104 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
> index e3695a0..9dd6c82 100644
> --- a/drivers/mmc/core/mmc.c
> +++ b/drivers/mmc/core/mmc.c
> @@ -536,6 +536,81 @@ static struct device_type mmc_type = {
> };
>
> /*
> + * Select the PowerClass for the current bus width
> + * If power class is defined for 4/8 bit bus in the
> + * extended CSD register, select it by executing the
> + * mmc_switch command.
> + */
> +static int mmc_select_powerclass(struct mmc_card *card,
> + unsigned int bus_width, u8 *ext_csd)
> +{
> + int err = 0;
> + unsigned int pwrclass_val;
> + unsigned int index = 0;
> + struct mmc_host *host = card->host;
> +
> + BUG_ON(!card);
If you're going to test the validity of card, do it before dereferencing
card->host above.
> + BUG_ON(!host);
> +
> + if (ext_csd == NULL)
> + return 0;
> + /* Power class selection is supported for versions >= 4.0 */
> + if (card->csd.mmca_vsn < CSD_SPEC_VER_4)
> + return 0;
> + /* Power class values are defined only for 4/8 bit bus */
> + if (bus_width == EXT_CSD_BUS_WIDTH_1)
> + return 0;
Let's add newlines before each comment line here.
> +
> + switch (1 << host->ios.vdd) {
> + case MMC_VDD_165_195:
> + if (host->ios.clock <= 2600)
> + index = EXT_CSD_PWR_CL_26_195;
> + else if (host->ios.clock <= 5200)
> + index = (bus_width <= EXT_CSD_BUS_WIDTH_8) ?
> + EXT_CSD_PWR_CL_52_195 :
> + EXT_CSD_PWR_CL_DDR_52_195;
> + else if (host->ios.clock <= 2)
> + index = EXT_CSD_PWR_CL_200_195;
> + break;
> + case MMC_VDD_32_33:
> + case MMC_VDD_33_34:
> + case MMC_VDD_34_35:
> + case MMC_VDD_35_36:
> + if (host->ios.clock <= 2600)
> + index = EXT_CSD_PWR_CL_26_360;
> + else if (host->ios.clock <= 5200)
> + index = (bus_width <= EXT_CSD_BUS_WIDTH_8) ?
> + EXT_CSD_PWR_CL_52_360 :
> + EXT_CSD_PWR_CL_DDR_52_360;
> + else if (host->ios.clock <= 2)
> + index = EXT_CSD_PWR_CL_200_360;
> + break;
> + default:
> + printk(KERN_ERR "votage range not supported\n");
(voltage, not votage)
This isn't good, because someone reading dmesg will have no idea that
this message came from MMC, and even if they know that it came from MMC,
they won't know which controller/card it came from.
I suggest:
pr_warning("%s: Voltage range not supported for power class.\n",
mmc_hostname(host));
> + break;
> + }
> +
> + pwrclass_val = ext_csd[index];
> +
> + if (bus_width & (EXT_CSD_BUS_WIDTH_8 | EXT_CSD_DDR_BUS_WIDTH_8))
> + pwrclass_val = (pwrclass_val & EXT_CSD_PWR_CL_8BIT_MASK) >>
> + EXT_CSD_PWR_CL_8BIT_SHIFT;
> + else
> + pwrclass_val = (pwrclass_val & EXT_CSD_PWR_CL_4BIT_MASK) >>
> + EXT_CSD_PWR_CL_4BIT_SHIFT;
> +
> + /*If the power class is different from the default value*/
Same comment -- leave spaces before the comment text. (I meant for you
to apply this comment to the whole patch.)
> + if (pwrclass_val > 0) {
> + err = mmc_switch(card, EXT_CSD_CMD_S
