[v2,3/4] mmc: dw_mmc: Convert to mmc_send_tuning()

On 20 December 2014 at 14:18, Alim Akhtar <alim.akhtar@gmail.com> wrote:
> Hi Ulf,
>
> On Mon, Dec 8, 2014 at 3:40 PM, Ulf Hansson <ulf.hansson@linaro.org> wrote:
>> On 6 December 2014 at 13:43, Alim Akhtar <alim.akhtar@gmail.com> wrote:
>>> Hi Ulf,
>>>
>>> On Fri, Dec 5, 2014 at 5:29 PM, Ulf Hansson <ulf.hansson@linaro.org> wrote:
>>>> Instead of having a local hack taking care of sending the tuning
>>>> command and as well to verify the response pattern, let's convert to
>>>> the common mmc_send_tuning() API.
>>>>
>>>> This change affects the Exynos variant, since it's the only one which
>>>> support the dw_mmc's ->execute_tuning() callback.
>>>>
>>>> Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
>>>> ---
>>>>
>>
>> Alim, thanks for helping out testing!
>>
>>> With this change HS200 mode does not work on exynos5800 peach-pi board.
>>> I got below error while testing this series:
>>>
>>> mmc0: tuning execution failed
>>> mmc0: error -5 whilst initialising MMC card
>>>
>>> Though, your's next branch with commit _a1d06b4_ works fine in HS200 mode.
>>
>> I was looking into the details of what change my patchset introduces
>> for dw_mmc-exynos. Apparently, dw_mmc-exynos was using the
>> MMC_STOP_TRANSMISSION to end the tuning reqeust (CMD21/19). The new
>> mmc_send_tuning() API doesn't, which also conforms to what the eMMC/SD
>> specifications states.
>>
>> Do you have any idea of why dw_mmc-exynos was using
>> MMC_STOP_TRANSMISSION for CMD19/21?
>>
>> To see if my theory is correct, could you try out the following patch
>> on top of $subject patch?
>> BTW, I have queued patch 1 and 2, from this patchset available on my
>> next branch.
>>
>>
>> From e1ac35bb0e90254275ec7088f41e6e2d59e48367 Mon Sep 17 00:00:00 2001
>> From: Ulf Hansson <ulf.hansson@linaro.org>
>> Date: Mon, 8 Dec 2014 10:58:48 +0100
>> Subject: [PATCH] mmc: core: End tuning request with stop command
>>
>> Not to be merged!
>>
>> This patch adds the MMC_STOP_TRANSMISSION command to end a tuning
>> request. For some reason dw_mmc seems to need this to complete the
>> tuning request without errors.
>>
>> Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
>> ---
>>  drivers/mmc/core/mmc_ops.c | 5 +++++
>>  1 file changed, 5 insertions(+)
>>
>> diff --git a/drivers/mmc/core/mmc_ops.c b/drivers/mmc/core/mmc_ops.c
>> index 3b044c5..aa79e0c 100644
>> --- a/drivers/mmc/core/mmc_ops.c
>> +++ b/drivers/mmc/core/mmc_ops.c
>> @@ -551,6 +551,7 @@ int mmc_send_tuning(struct mmc_host *host)
>>  {
>>         struct mmc_request mrq = {NULL};
>>         struct mmc_command cmd = {0};
>> +       struct mmc_command stop = {0};
>>         struct mmc_data data = {0};
>>         struct scatterlist sg;
>>         struct mmc_ios *ios = &host->ios;
>> @@ -576,10 +577,14 @@ int mmc_send_tuning(struct mmc_host *host)
>>
>>         mrq.cmd = &cmd;
>>         mrq.data = &data;
>> +       mrq.stop = &stop;
>>
>>         cmd.opcode = opcode;
>>         cmd.flags = MMC_RSP_R1 | MMC_CMD_ADTC;
>>
>> +       stop.opcode = MMC_STOP_TRANSMISSION;
>> +       stop.flags = MMC_RSP_R1B | MMC_CMD_AC;
>> +
>>         data.blksz = size;
>>         data.blocks = 1;
>>         data.flags = MMC_DATA_READ;
>> --
>> 1.9.1
>>
> Sorry for delay in testing this suggested patch, I would say this
> certainly helps, but still I need to change sample phase to make it
> work with generic tuning function.
> So with your's adding STOP_TRANSMISSION command and below change,
> HS200 works well on exynos5800
>
> diff --git a/arch/arm/boot/dts/exynos5800-peach-pi.dts
> b/arch/arm/boot/dts/exynos5800-peach-pi.dts
> index e8fdda8..e0f0337 100644
> --- a/arch/arm/boot/dts/exynos5800-peach-pi.dts
> +++ b/arch/arm/boot/dts/exynos5800-peach-pi.dts
> @@ -555,7 +555,7 @@
>         card-detect-delay = <200>;
>         clock-frequency = <400000000>;
>         samsung,dw-mshc-ciu-div = <3>;
> -       samsung,dw-mshc-sdr-timing = <0 4>;
> +       samsung,dw-mshc-sdr-timing = <2 4>;
>
> This basically change the clock-sample phase with which the tuning
> process starts.
>
> I didn't find anything is exynos documentations which suggest
> STOP_TRANSMISSION is needed, may be Seungwon might be know as he wrote
> this.
>
> Are you ok to add STOP_TRANSMISSION in generic tuning code (probably
> with a quirk, so that other hosts are still happy)?

No, I don't want that.

If special treatment are needed for dw_mmc to handle a tuning request,
dw_mmc should be able to take care by itself. How about below patch,
do you think that could work?

From c2e5783beaa322178f2336b4bff4bdf13da76f56 Mon Sep 17 00:00:00 2001
From: Ulf Hansson <ulf.hansson@linaro.org>
Date: Mon, 22 Dec 2014 15:24:14 +0100
Subject: [PATCH] mmc: dw_mmc: Generate stop commands for failed tuning
 requests

It's seems like dw_mmc internal logic expects failed data transfers to
be ended using a stop command. Let the tuning requests also fall into
this category, since there are data transfer involved.

Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
---
 drivers/mmc/host/dw_mmc.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

                stop->flags = MMC_RSP_R1B | MMC_CMD_AC;

On 23 December 2014 at 10:49, Jaehoon Chung <jh80.chung@samsung.com> wrote:
> Hi. Ulf.
>
> Your patch has bug..
> If last sample value is failed, then it's returned with error.
>
> I will recommend this. how about?
>
>  drivers/mmc/host/dw_mmc-exynos.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/mmc/host/dw_mmc-exynos.c b/drivers/mmc/host/dw_mmc-exynos.c
> index d0d7aec..d6b8846 100644
> --- a/drivers/mmc/host/dw_mmc-exynos.c
> +++ b/drivers/mmc/host/dw_mmc-exynos.c
> @@ -381,7 +381,7 @@ static int dw_mci_exynos_execute_tuning(struct dw_mci_slot *slot)
>         struct mmc_host *mmc = slot->mmc;
>         u8 start_smpl, smpl, candiates = 0;
>         s8 found = -1;
> -       int ret = 0;
> +       int ret = 0, success;
>
>         start_smpl = dw_mci_exynos_get_clksmpl(host);
>
> @@ -389,8 +389,8 @@ static int dw_mci_exynos_execute_tuning(struct dw_mci_slot *slot)
>                 mci_writel(host, TMOUT, ~0);
>                 smpl = dw_mci_exynos_move_next_clksmpl(host);
>
> -               ret = mmc_send_tuning(mmc);
> -               if (!ret)
> +               success = mmc_send_tuning(mmc);
> +               if (!success)
>                         candiates |= (1 << smpl);
>
>         } while (start_smpl != smpl);
> --
> 1.9.1
>

Urgh! Thanks a lot for spotting this Jaehoon! I will update my patch
according to your proposal. Sorry for all the noise I caused around
this.

Kind regards
Uffe
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