On Fri, March 21, 2014, Ulf Hansson wrote:
> On 14 March 2014 13:16, Seungwon Jeon <[email protected]> wrote:
> > Current implementation for bus speed mode selection is too
> > complicated. This patch is to simplify the codes and remove
> > some duplicate parts.
>
> Really appreciate you taking on this task!
>
> >
> > The following changes are including:
> > * Adds functions for each mode selection(HS, HS-DDR, HS200 and etc)
> > * Rearranged the mode selection sequence with supported device type
> > * Adds maximum speed for HS200 mode(hs200_max_dtr)
> > * Adds field definition for HS_TIMING of EXT_CSD
> >
> > Signed-off-by: Seungwon Jeon <[email protected]>
> > Tested-by: Jaehoon Chung <[email protected]>
> > Acked-by: Jaehoon Chung <[email protected]>
> > ---
> > drivers/mmc/core/debugfs.c | 2 +-
> > drivers/mmc/core/mmc.c | 431
> > ++++++++++++++++++++++++--------------------
> > include/linux/mmc/card.h | 1 +
> > include/linux/mmc/mmc.h | 4 +
> > 4 files changed, 238 insertions(+), 200 deletions(-)
> >
> > diff --git a/drivers/mmc/core/debugfs.c b/drivers/mmc/core/debugfs.c
> > index 509229b..1f730db 100644
> > --- a/drivers/mmc/core/debugfs.c
> > +++ b/drivers/mmc/core/debugfs.c
> > @@ -139,7 +139,7 @@ static int mmc_ios_show(struct seq_file *s, void *data)
> > str = "mmc DDR52";
> > break;
> > case MMC_TIMING_MMC_HS200:
> > - str = "mmc high-speed SDR200";
> > + str = "mmc HS200";
> > break;
> > default:
> > str = "invalid";
> > diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
> > index 480c100..6dd68e6 100644
> > --- a/drivers/mmc/core/mmc.c
> > +++ b/drivers/mmc/core/mmc.c
> > @@ -242,7 +242,7 @@ static void mmc_select_card_type(struct mmc_card *card)
> > struct mmc_host *host = card->host;
> > u8 card_type = card->ext_csd.raw_card_type & EXT_CSD_CARD_TYPE_MASK;
> > u32 caps = host->caps, caps2 = host->caps2;
> > - unsigned int hs_max_dtr = 0;
> > + unsigned int hs_max_dtr = 0, hs200_max_dtr = 0;
> > unsigned int avail_type = 0;
> >
> > if (caps & MMC_CAP_MMC_HIGHSPEED &&
> > @@ -271,17 +271,18 @@ static void mmc_select_card_type(struct mmc_card
> > *card)
> >
> > if (caps2 & MMC_CAP2_HS200_1_8V_SDR &&
> > card_type & EXT_CSD_CARD_TYPE_HS200_1_8V) {
> > - hs_max_dtr = MMC_HS200_MAX_DTR;
> > + hs200_max_dtr = MMC_HS200_MAX_DTR;
> > avail_type |= EXT_CSD_CARD_TYPE_HS200_1_8V;
> > }
> >
> > if (caps2 & MMC_CAP2_HS200_1_2V_SDR &&
> > card_type & EXT_CSD_CARD_TYPE_HS200_1_2V) {
> > - hs_max_dtr = MMC_HS200_MAX_DTR;
> > + hs200_max_dtr = MMC_HS200_MAX_DTR;
> > avail_type |= EXT_CSD_CARD_TYPE_HS200_1_2V;
> > }
> >
> > card->ext_csd.hs_max_dtr = hs_max_dtr;
> > + card->ext_csd.hs200_max_dtr = hs200_max_dtr;
> > card->mmc_avail_type = avail_type;
> > }
> >
> > @@ -833,37 +834,46 @@ static int mmc_select_powerclass(struct mmc_card
> > *card)
> > }
> >
> > /*
> > - * Selects the desired buswidth and switch to the HS200 mode
> > - * if bus width set without error
> > + * Set the bus speed for the selected speed mode.
> > */
> > -static int mmc_select_hs200(struct mmc_card *card)
> > +static void mmc_set_bus_speed(struct mmc_card *card)
> > +{
> > + unsigned int max_dtr = (unsigned int)-1;
>
> I guess this is to silence compile warnings? Why not just:
> unsigned int max_dtr = 0;
Basically, I made an effort to keep the previous codes if it's not a problem.
If you found something wrong, please let me know.
>
> > +
> > + if (mmc_card_hs200(card) && max_dtr > card->ext_csd.hs200_max_dtr)
> > + max_dtr = card->ext_csd.hs200_max_dtr;
> > + else if (mmc_card_hs(card) && max_dtr > card->ext_csd.hs_max_dtr)
> > + max_dtr = card->ext_csd.hs_max_dtr;
> > + else if (max_dtr > card->csd.max_dtr)
> > + max_dtr = card->csd.max_dtr;
> > +
> > + mmc_set_clock(card->host, max_dtr);
> > +}
> > +
> > +/*
> > + * Select the bus width amoung 4-bit and 8-bit(SDR).
> > + * If the bus width is changed successfully, return the slected width
> > value.
> > + * Zero is returned instead of error value if the wide width is not
> > supported.
> > + */
> > +static int mmc_select_bus_width(struct mmc_card *card)
> > {
> > - int idx, err = -EINVAL;
> > - struct mmc_host *host;
> > static unsigned ext_csd_bits[] = {
> > - EXT_CSD_BUS_WIDTH_4,
> > EXT_CSD_BUS_WIDTH_8,
> > + EXT_CSD_BUS_WIDTH_4,
> > };
> > static unsigned bus_widths[] = {
> > - MMC_BUS_WIDTH_4,
> > MMC_BUS_WIDTH_8,
> > + MMC_BUS_WIDTH_4,
> > };
>
> Do we really need to keep these arrays? The only contain only two values.
>
> Can't we just try with 8-bit, if supported, and if it fails try with
> 4-bit. Would that further simplify the code?
Yes, current implementation does that.
First, it tries with 8-bit if supported, and if failed, it will be tried with
4-bit.
And I think using array can make simple retry coding if considering failure
case.
I intended to keep original way.
>
> Overall looks good to me, besides the minor comments above.
>
> Since this kind of touches quite old code, I would appreciate if it
> could go though some more testing in linux next, thus it's material
> for early queueing to 3.16.
>
> But before we go on, I would like to know if you managed to test all
> the different variants of buswidth/speedmode and the bus width test?
> If there is any specific test would like to get help to run, just tell
> me.
>
> Nice work!
It would be nice if it's picked for 3.15.
As I mentioned above, I basically kept the original flow and way.
This change applies only to eMMC type and participates only in card
initialization's process.
I tested on the following various mode and detection is performed successfully.
- HS400 w/ 8-bit
- HS400 w/ 4-bit : HS200 mode is selected(Because HS400 is possible with
8-bit)
- HS200 w/ 4-bit or 8-bit
- DDR52 w/ 4-bit or 8-bit
- High speed w/ 1-bit, 4-bit or 8-bit
- Backwards w/ 1-bit, 4-bit or 8-bit
I really appreciate your deep reviews.
Thanks,
Seungwon Jeon
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