linux-kernel - Re: [PATCH v3] mmc: dw_mmc: Add MSHC compatible for Exynos4412

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Date:	Tue, 19 Feb 2013 22:10:32 +0530
From:	Alim Akhtar <alim.akhtar@...il.com>
To:	Dongjin Kim <tobetter@...il.com>
Cc:	Seungwon Jeon <tgih.jun@...sung.com>,
	"'unlisted-recipients:'"@samsung.com,
	"'no To-header on input'"@samsung.com,
	Jaehoon Chung <jh80.chung@...sung.com>,
	Sachin Kamat <sachin.kamat@...aro.org>,
	Chris Ball <cjb@...top.org>, Arnd Bergmann <arnd@...db.de>,
	Thomas Abraham <thomas.abraham@...aro.org>,
	Will Newton <will.newton@...tec.com>,
	linux-mmc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] mmc: dw_mmc: Add MSHC compatible for Exynos4412

Hi,

On Tue, Feb 19, 2013 at 6:04 PM, Dongjin Kim <tobetter@...il.com> wrote:
> Hello Seungwon,
>
> Thank you for reviewing and I understand what you mean.
>
> I agree that Exynos5250 and Exynos4412 are not same, no idea how much
> they are different because no Exynos5250 spec on my hand. But at least
> I assumed that the capabilities below are supported by Exynos4412 in
> terms of its datasheet and it does work on my end as expected. :) Also
> I assumed it will be separated if one of both become different to add
> more capabilities.
>
>         MMC_CAP_UHS_DDR50 | MMC_CAP_1_8V_DDR |
>                MMC_CAP_8_BIT_DATA | MMC_CAP_CMD23,
>
> Maybe my understanding or approach is wrong since I do not have the
> information of Exynos5250.
> And suggestion do you have?

Recently Guennadi Liakhovetski has done some work to centralize the
mmc capabilities. See [1] and [2].
Those patches are pushed to Chris's mmc-next tree.
Is  it possible to extend [1] and [2] and add more capabilities (at
least all known one) and let these caps being passed from DT instead?

Second thought is, let the common minimum caps as a part of .caps
field in dw_mmc-exynos.c itself and pass the extra/advance controller
caps from DT and parse them via dw_mci_parse_dt() in dw_mmc.c itself.

[1] https://patchwork.kernel.org/patch/1991851/
[2] https://patchwork.kernel.org/patch/2106531/

> Regards,
> Dongjin.
>
> On Tue, Feb 19, 2013 at 7:19 PM, Seungwon Jeon <tgih.jun@...sung.com> wrote:
>> On Tuesday, February 19, 2013, Dongjin Kim wrote:
>>> This patch adds the compatible string for MSHC controller of Exynos4412, and
>>> share the controller specific properties with Exynos5250 since they have same
>>> features. Its driver data name is changed to exynos_drv_data instead SoC
>>> specific name.
>>
>> It's not actually same.
>> Exynos4412 doesn't have forward compatibilities for Exynos5250.
>> I agree that functionality of exynos_drv_data is common.
>> These functions have been implemented for existing Exynos*.
>> But in case of caps, it can't applied completely.
>> I'm concerning about this.
>>
>> Thanks,
>> Seungwon Jeon
>>>
>>> Cc: Jaehoon Chung <jh80.chung@...sung.com>
>>> Cc: Sachin Kamat <sachin.kamat@...aro.org>
>>> Signed-off-by: Dongjin Kim <tobetter@...il.com>
>>> ---
>>>  drivers/mmc/host/dw_mmc-exynos.c |   12 +++++++-----
>>>  1 file changed, 7 insertions(+), 5 deletions(-)
>>>
>>> diff --git a/drivers/mmc/host/dw_mmc-exynos.c b/drivers/mmc/host/dw_mmc-exynos.c
>>> index 4d50da6..38cd03c 100644
>>> --- a/drivers/mmc/host/dw_mmc-exynos.c
>>> +++ b/drivers/mmc/host/dw_mmc-exynos.c
>>> @@ -199,8 +199,8 @@ static int dw_mci_exynos_setup_bus(struct dw_mci *host,
>>>       return 0;
>>>  }
>>>
>>> -/* Exynos5250 controller specific capabilities */
>>> -static unsigned long exynos5250_dwmmc_caps[4] = {
>>> +/* Exynos4412/Exynos5250 controller specific capabilities */
>>> +static unsigned long exynos_dwmmc_caps[4] = {
>>>       MMC_CAP_UHS_DDR50 | MMC_CAP_1_8V_DDR |
>>>               MMC_CAP_8_BIT_DATA | MMC_CAP_CMD23,
>>>       MMC_CAP_CMD23,
>>> @@ -208,8 +208,8 @@ static unsigned long exynos5250_dwmmc_caps[4] = {
>>>       MMC_CAP_CMD23,
>>>  };
>>>
>>> -static const struct dw_mci_drv_data exynos5250_drv_data = {
>>> -     .caps                   = exynos5250_dwmmc_caps,
>>> +static const struct dw_mci_drv_data exynos_drv_data = {
>>> +     .caps                   = exynos_dwmmc_caps,
>>>       .init                   = dw_mci_exynos_priv_init,
>>>       .setup_clock            = dw_mci_exynos_setup_clock,
>>>       .prepare_command        = dw_mci_exynos_prepare_command,
>>> @@ -219,8 +219,10 @@ static const struct dw_mci_drv_data exynos5250_drv_data = {
>>>  };
>>>
>>>  static const struct of_device_id dw_mci_exynos_match[] = {
>>> +     { .compatible = "samsung,exynos4412-dw-mshc",
>>> +                     .data = &exynos_drv_data, },
>>>       { .compatible = "samsung,exynos5250-dw-mshc",
>>> -                     .data = &exynos5250_drv_data, },
>>> +                     .data = &exynos_drv_data, },
>>>       {},
>>>  };
>>>  MODULE_DEVICE_TABLE(of, dw_mci_exynos_match);
>>> --
>>> 1.7.10.4
>>>
>>> --
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>>
> --
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-- 
Regards,
Alim
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