[PATCH v2 01/13] drm/bridge: samsung-dsim: separate LINK and DPHY status registers

[Inki Dae]

2025년 6월 27일 (금) 오전 4:42, Kaustabh Chakraborty <kauschluss at disroot.org>님이 작성:
>
> Exynos7870's DSIM has separate registers for LINK and DPHY status. This
> is in contrast to other devices in the driver which use a single
> register for both.
>
> Add their respective entries in the register list. Devices having a
> single status register have been assigned the same offset for both
> entries.
>
> Signed-off-by: Kaustabh Chakraborty <kauschluss at disroot.org>
> ---
>  drivers/gpu/drm/bridge/samsung-dsim.c | 15 +++++++++------
>  1 file changed, 9 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/gpu/drm/bridge/samsung-dsim.c b/drivers/gpu/drm/bridge/samsung-dsim.c
> index f2f666b27d2d5ec016d7a7f47c87fcdf1377d41a..7fd4c34cdc3170d363942f98feec048097da3c06 100644
> --- a/drivers/gpu/drm/bridge/samsung-dsim.c
> +++ b/drivers/gpu/drm/bridge/samsung-dsim.c
> @@ -30,7 +30,7 @@
>  /* returns true iff both arguments logically differs */
>  #define NEQV(a, b) (!(a) ^ !(b))
>
> -/* DSIM_STATUS */
> +/* DSIM_DPHY_STATUS */
>  #define DSIM_STOP_STATE_DAT(x)         (((x) & 0xf) << 0)
>  #define DSIM_STOP_STATE_CLK            BIT(8)
>  #define DSIM_TX_READY_HS_CLK           BIT(10)
> @@ -239,7 +239,8 @@ enum samsung_dsim_transfer_type {
>  };
>
>  enum reg_idx {
> -       DSIM_STATUS_REG,        /* Status register */

According to the datasheets I have, both Exynos5422 and Exynos7420 use
DSIM_STATUS, while Exynos8890 splits this into DSIM_LINK_STATUS and
DSIM_PHY_STATUS. It appears that Exynos7870 follows the same approach
as Exynos8890.

The current modification removes the legacy DSIM_STATUS_REG and adds
new DSIM_LINK_STATUS_REG and DSIM_DPHY_STATUS_REG. However, this
change causes the register names used for older SoC versions to differ
from those in the datasheets, so I think it is better to keep the
legacy name for backward compatibility.

How about modifying it as follows?
enum reg_idx {
    DSIM_STATUS_REG,          /* Status register (legacy) */
    DSIM_LINK_STATUS_REG,     /* Link status register (Exynos7870, ...) */
    DSIM_PHY_STATUS_REG,      /* PHY status register (Exynos7870, ...) */
    ...
};

static const unsigned int exynos7870_reg_ofs[] = {
    [DSIM_STATUS_REG] = 0x00,        /* Legacy compatibility - use
LINK_STATUS */
    [DSIM_LINK_STATUS_REG] = 0x04,   /* Link status register */
    [DSIM_PHY_STATUS_REG] = 0x08,    /* PHY status register */
    ...
};

Additionally, by configuring the hw_type field in the
samsung_dsim_plat_data structure like you did with the patch[1], you
can use the appropriate register name for each SoC as shown below:
if (dsi->plat_data->hw_type == DSIM_TYPE_EXYNOS7870)
    reg = samsung_dsim_read(dsi, DSIM_LINK_STATUS_REG);
else
    reg = samsung_dsim_read(dsi, DSIM_STATUS_REG);


[1] [PATCH v2 12/13] drm/bridge: samsung-dsim: add driver support for
exynos7870 DSIM bridge

Thanks,
Inki Dae


> +       DSIM_LINK_STATUS_REG,   /* Link status register */
> +       DSIM_DPHY_STATUS_REG,   /* D-PHY status register */
>         DSIM_SWRST_REG,         /* Software reset register */
>         DSIM_CLKCTRL_REG,       /* Clock control register */
>         DSIM_TIMEOUT_REG,       /* Time out register */
> @@ -264,7 +265,8 @@ enum reg_idx {
>  };
>
>  static const unsigned int exynos_reg_ofs[] = {
> -       [DSIM_STATUS_REG] =  0x00,
> +       [DSIM_LINK_STATUS_REG] =  0x00,
> +       [DSIM_DPHY_STATUS_REG] =  0x00,
>         [DSIM_SWRST_REG] =  0x04,
>         [DSIM_CLKCTRL_REG] =  0x08,
>         [DSIM_TIMEOUT_REG] =  0x0c,
> @@ -288,7 +290,8 @@ static const unsigned int exynos_reg_ofs[] = {
>  };
>
>  static const unsigned int exynos5433_reg_ofs[] = {
> -       [DSIM_STATUS_REG] = 0x04,
> +       [DSIM_LINK_STATUS_REG] = 0x04,
> +       [DSIM_DPHY_STATUS_REG] = 0x04,
>         [DSIM_SWRST_REG] = 0x0C,
>         [DSIM_CLKCTRL_REG] = 0x10,
>         [DSIM_TIMEOUT_REG] = 0x14,
> @@ -690,7 +693,7 @@ static unsigned long samsung_dsim_set_pll(struct samsung_dsim *dsi,
>                         dev_err(dsi->dev, "PLL failed to stabilize\n");
>                         return 0;
>                 }
> -               reg = samsung_dsim_read(dsi, DSIM_STATUS_REG);
> +               reg = samsung_dsim_read(dsi, DSIM_LINK_STATUS_REG);
>         } while ((reg & DSIM_PLL_STABLE) == 0);
>
>         dsi->hs_clock = fout;
> @@ -966,7 +969,7 @@ static int samsung_dsim_init_link(struct samsung_dsim *dsi)
>                         return -EFAULT;
>                 }
>
> -               reg = samsung_dsim_read(dsi, DSIM_STATUS_REG);
> +               reg = samsung_dsim_read(dsi, DSIM_DPHY_STATUS_REG);
>                 if ((reg & DSIM_STOP_STATE_DAT(lanes_mask))
>                     != DSIM_STOP_STATE_DAT(lanes_mask))
>                         continue;
>
> --
> 2.49.0
>
>