On 18 April 2018 at 11:56, Simon Horman <horms+renesas@xxxxxxxxxxxx> wrote:
> This adds two new HS400 tuning operations:
> * prepare_hs400_tuning_downgrade
> * complete_hs400_tuning
>
> These supplement the existing HS400 operation:
> * prepare_hs400_tuning
>
> This is motivated by a requirement of Renesas SDHI for the following:
> 1. Disabling SCC before selecting to HS if selection of HS400 has occurred.
> This can be done in an implementation of prepare_hs400_tuning_downgrade
> 2. Updating registers after switching to HS400
> This can be done in an implementation of complete_hs400_tuning
>
> After this patch the call sequence is as follows:
>
> * Initial tuning
> i. prepare_hs400_tuning
> 2. Tuning procedure
> 3. Select HS400
> 4. complete_hs400_tuning
>
> * Retune
> 1. prepare_hs400_tuning_downgrade
> 2. Select HS200
> 3. prepare_hs400_tuning
> 4. Tuning procedure
> 5. Select HS400
> 6. complete_hs400_tuning
>
> If prepare_hs400_tuning or complete_hs400_tuning are not implemented they
> are not called. And if neither are called the procedure is the same as
> before this patch.
>
> Design consideration: In the case of Renesas SDHI it is likely that
> prepare_hs400_tuning_downgrade and prepare_hs400_tuning could be combined
> if the latter was called before selecting HS200 during tuning. When I say
> likely, I believe it matches my understanding of the hardware. However, I
> did not test this as I am entirely unsure if moving the
> prepare_hs400_tuning call would work for other hardware that uses this
> operation and I am in no position to test such hardware.
>
> Signed-off-by: Simon Horman <horms+renesas@xxxxxxxxxxxx>
> ---
> v4
> * New patch
> ---
> drivers/mmc/core/host.c | 13 ++++++++++++-
> drivers/mmc/core/mmc.c | 19 ++++++++++++++-----
> include/linux/mmc/host.h | 26 +++++++++++++++++++++++++-
> 3 files changed, 51 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/mmc/core/host.c b/drivers/mmc/core/host.c
> index 64b03d6eaf18..5e60df7ca11f 100644
> --- a/drivers/mmc/core/host.c
> +++ b/drivers/mmc/core/host.c
> @@ -138,6 +138,10 @@ int mmc_retune(struct mmc_host *host)
> host->doing_retune = 1;
>
> if (host->ios.timing == MMC_TIMING_MMC_HS400) {
> + if (host->ops->prepare_hs400_tuning_downgrade)
> + host->ops->prepare_hs400_tuning_downgrade(host,
> + &host->ios);
> +
Quite a long lame for the callback, perhaps "hs400_downgrade" is sufficient?
Moreover, I suggest you move this new code snippet into
mmc_hs400_to_hs200() instead.
> err = mmc_hs400_to_hs200(host->card);
> if (err)
> goto out;
> @@ -152,8 +156,15 @@ int mmc_retune(struct mmc_host *host)
> if (err)
> goto out;
>
> - if (return_to_hs400)
> + if (return_to_hs400) {
> err = mmc_hs200_to_hs400(host->card);
> + if (err)
> + goto out;
> +
> + if (host->ops->complete_hs400_tuning)
> + host->ops->complete_hs400_tuning(host, &host->ios);
Perhaps rename callback to "hs400_complete"?
And, please move this new code into mmc_select_hs400() (which is
called from mmc_hs200_to_hs400()), as I think it better belongs there.
> + }
> +
> out:
> host->doing_retune = 0;
>
> diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
> index 099b327e10ca..a108a1a3e27f 100644
> --- a/drivers/mmc/core/mmc.c
> +++ b/drivers/mmc/core/mmc.c
> @@ -1508,22 +1508,31 @@ static int mmc_select_timing(struct mmc_card *card)
> static int mmc_hs200_tuning(struct mmc_card *card)
> {
> struct mmc_host *host = card->host;
> + bool run_hs400_ops;
> int err;
>
> + run_hs400_ops = card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS400 &&
> + host->ios.bus_width == MMC_BUS_WIDTH_8;
> +
> /*
> * Timing should be adjusted to the HS400 target
> * operation frequency for tuning process
> */
> - if (card->mmc_avail_type & EXT_CSD_CARD_TYPE_HS400 &&
> - host->ios.bus_width == MMC_BUS_WIDTH_8)
> - if (host->ops->prepare_hs400_tuning)
> - host->ops->prepare_hs400_tuning(host, &host->ios);
> + if (run_hs400_ops && host->ops->prepare_hs400_tuning)
> + host->ops->prepare_hs400_tuning(host, &host->ios);
>
> err = mmc_execute_tuning(card);
> if (err)
> return err;
>
> - return mmc_select_hs400(card);
> + err = mmc_select_hs400(card);
> + if (err)
> + return err;
> +
> + if (run_hs400_ops && host->ops->complete_hs400_tuning)
> + host->ops->complete_hs400_tuning(host, &host->ios);
> +
I would suggest you to drop patch 1, then re-base $subject patch on
top of the patch I just sent ("mmc: core: Move calls to
->prepare_hs400_tuning() closer to mmc code").
In this way, we get less card specific code in mmc_retune(), which is
desirable - and in the end I think the code becomes a bit more easy to
understand.
> + return 0;
> }
>
> /*
> diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
> index 85146235231e..5d3ae1071d2f 100644
> --- a/include/linux/mmc/host.h
> +++ b/include/linux/mmc/host.h
> @@ -143,8 +143,32 @@ struct mmc_host_ops {
> /* The tuning command opcode value is different for SD and eMMC cards */
> int (*execute_tuning)(struct mmc_host *host, u32 opcode);
>
> - /* Prepare HS400 target operating frequency depending host driver */
> + /* Prepare for HS400 downgrade during tuning of target operating frequency depending on host driver
> + * If provided and retuning is in progress, this is called before:
> + * 1. Switching from HS400 to HS200; which preceeds
> + * 2. Calling .prepare_hs400_tuning, if present; which preceeds
> + * 3. The HS400 tuning procedure
> + */
> + void (*prepare_hs400_tuning_downgrade)(struct mmc_host *host, struct mmc_ios *ios);
> +
> + /* Prepare for tuning HS400 target operating frequency depending on host driver
> + * If provided, this called:
> + * - In the case that retuning is in progress, after:
> + * 1. .prepare_hs400_tuning_downgrade(), if present
> + * 2. Switching from HS400 to HS200
> + * - And in any case before:
> + * 3. The HS400 tuning procedure
> + */
> +
> int (*prepare_hs400_tuning)(struct mmc_host *host, struct mmc_ios *ios);
> +
> + /* Complete tuning HS400 target operating frequency depending host driver
> + * If provided, this is called after:
> + * 1. The HS400 tuning procedure
> + * 2. Switching from HS200 to HS400
> + */
> + void (*complete_hs400_tuning)(struct mmc_host *host, struct mmc_ios *ios);
> +
> /* Prepare enhanced strobe depending host driver */
> void (*hs400_enhanced_strobe)(struct mmc_host *host,
> struct mmc_ios *ios);
> --
> 2.11.0
>
Otherwise, as said, I like the approach.
Kind regards
Uffe
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