linux-kernel - Re: [PATCH v3 10/13] mmc: mmci: add Qcom specifics of clk and datactrl registers.

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Date:	Mon, 26 May 2014 15:05:30 +0200
From:	Ulf Hansson <ulf.hansson@...aro.org>
To:	Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
Cc:	Russell King <linux@....linux.org.uk>,
	linux-mmc <linux-mmc@...r.kernel.org>,
	Chris Ball <chris@...ntf.net>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	linux-arm-msm@...r.kernel.org,
	Linus Walleij <linus.walleij@...aro.org>
Subject: Re: [PATCH v3 10/13] mmc: mmci: add Qcom specifics of clk and
 datactrl registers.

On 23 May 2014 14:52,  <srinivas.kandagatla@...aro.org> wrote:
> From: Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
>
> This patch adds specifics of clk and datactrl register on Qualcomm SD
> Card controller. This patch also populates the Qcom variant data with
> these new values specific to Qualcomm SD Card Controller.
>
> Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
> Reviewed-by: Linus Walleij <linus.walleij@...aro.org>
> ---
>  drivers/mmc/host/mmci.c |  4 ++++
>  drivers/mmc/host/mmci.h | 24 ++++++++++++++++++++++++
>  2 files changed, 28 insertions(+)
>
> diff --git a/drivers/mmc/host/mmci.c b/drivers/mmc/host/mmci.c
> index 17e7f6a..6434f5b1 100644
> --- a/drivers/mmc/host/mmci.c
> +++ b/drivers/mmc/host/mmci.c
> @@ -185,6 +185,10 @@ static struct variant_data variant_qcom = {
>         .fifosize               = 16 * 4,
>         .fifohalfsize           = 8 * 4,
>         .clkreg                 = MCI_CLK_ENABLE,
> +       .clkreg_enable          = MCI_QCOM_CLK_FLOWENA |
> +                                 MCI_QCOM_CLK_FEEDBACK_CLK,

Obviously I don't have the in-depth knowledge about the Qcom variant,
but comparing the ST variant here made me think.

Using the feeback clock internal logic in the ST variant, requires the
corresponding feedback clock pin signal on the board, to be
routed/connected. Typically we used this for SD cards, which involved
using an external level shifter circuit.

Is it correct to enable this bit for all cases, including eMMC?

If it is board specific configurations, you should add a DT binding
for it - like there are for the ST variant.

> +       .clkreg_8bit_bus_enable = MCI_QCOM_CLK_WIDEBUS_8,
> +       .datactrl_mask_ddrmode  = MCI_QCOM_CLK_DDR_MODE,
>         .blksz_datactrl4        = true,
>         .datalength_bits        = 24,
>         .blksz_datactrl4        = true,
> diff --git a/drivers/mmc/host/mmci.h b/drivers/mmc/host/mmci.h
> index cd83ca3..1b93ae7 100644
> --- a/drivers/mmc/host/mmci.h
> +++ b/drivers/mmc/host/mmci.h
> @@ -41,6 +41,22 @@
>  /* Modified PL180 on Versatile Express platform */
>  #define MCI_ARM_HWFCEN         BIT(12)
>
> +/* Modified on Qualcomm Integrations */
> +#define MCI_QCOM_CLK_WIDEBUS_4 (2 << 10)

This is the same as BIT(11), please use MCI_4BIT_BUS instead.

> +#define MCI_QCOM_CLK_WIDEBUS_8 (3 << 10)

Since you converted to use the "BIT" macro a few patches ago, I
suggest we should stick to it. How about something below:

#define MCI_QCOM_CLK_WIDEBUS_8 BIT (BIT(10) | BIT(11))

Please adopt all defines added in this patch to use the BIT macro.

> +#define MCI_QCOM_CLK_FLOWENA   BIT(12)
> +#define MCI_QCOM_CLK_INVERTOUT BIT(13)
> +
> +/* select in latch data and command */
> +#define MCI_QCOM_CLK_SEL_IN_SHIFT      (14)

BIT (14)?

> +#define MCI_QCOM_CLK_SEL_MASK          (0x3)
> +#define MCI_QCOM_CLK_SEL_RISING_EDGE   (1)

BIT(1)?

> +#define MCI_QCOM_CLK_FEEDBACK_CLK      (2 << 14)
> +#define MCI_QCOM_CLK_DDR_MODE          (3 << 14)
> +
> +/* mclk selection */
> +#define MCI_QCOM_CLK_SEL_MCLK          (2 << 23)

Does this correspond to MCI_CLK_BYPASS? If so, we should maybe state
this in a comment?

> +
>  #define MMCIARGUMENT           0x008
>  #define MMCICOMMAND            0x00c
>  #define MCI_CPSM_RESPONSE      BIT(6)
> @@ -54,6 +70,14 @@
>  #define MCI_ST_NIEN            BIT(13)
>  #define MCI_ST_CE_ATACMD       BIT(14)
>
> +/* Modified on Qualcomm Integrations */
> +#define MCI_QCOM_CSPM_DATCMD           BIT(12)
> +#define MCI_QCOM_CSPM_MCIABORT         BIT(13)
> +#define MCI_QCOM_CSPM_CCSENABLE                BIT(14)
> +#define MCI_QCOM_CSPM_CCSDISABLE       BIT(15)
> +#define MCI_QCOM_CSPM_AUTO_CMD19       BIT(16)
> +#define MCI_QCOM_CSPM_AUTO_CMD21       BIT(21)
> +
>  #define MMCIRESPCMD            0x010
>  #define MMCIRESPONSE0          0x014
>  #define MMCIRESPONSE1          0x018
> --
> 1.9.1
>

Kind regards
Ulf Hansson
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