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SubjectRe: [PATCH 1/1] Support LVDS output on Allwinner A20
Hi,

On Mon, Feb 10, 2020 at 09:56:33PM +0200, Andrey Lebedev wrote:
> A20 SoC (found in Cubieboard 2 among others) requires different LVDS set
> up procedure than A33. Timing controller (tcon) driver only implements
> sun6i-style procedure, that doesn't work on A20 (sun7i).

You're missing your Signed-off-by here.

> The support for such procedure is ported from u-boot and follows u-boot
> naming convention: SUN6I* for sun6i-style procedure, and SUN4I for other
> (which happens to be compatible with A20).

A commit log is mostly about why you're doing a change, this part can
be left out.

> ---
> drivers/gpu/drm/sun4i/sun4i_tcon.c | 91 ++++++++++++++++++++----------
> drivers/gpu/drm/sun4i/sun4i_tcon.h | 12 ++++
> 2 files changed, 73 insertions(+), 30 deletions(-)
>
> diff --git a/drivers/gpu/drm/sun4i/sun4i_tcon.c b/drivers/gpu/drm/sun4i/sun4i_tcon.c
> index c81cdce6ed55..78896e907ca9 100644
> --- a/drivers/gpu/drm/sun4i/sun4i_tcon.c
> +++ b/drivers/gpu/drm/sun4i/sun4i_tcon.c
> @@ -114,46 +114,74 @@ static void sun4i_tcon_channel_set_status(struct sun4i_tcon *tcon, int channel,
> }
> }
>
> +static void sun4i_tcon_lvds_sun6i_enable(struct sun4i_tcon *tcon,
> + const struct drm_encoder *encoder) {

This doesn't match the kernel coding style, make sure to run checkpatch.

Also, using something like sun6i_tcon_setup_lvds_phy would be more fit
to what this function is doing.

> + u8 val;
> + regmap_write(tcon->regs, SUN4I_TCON0_LVDS_ANA0_REG,
> + SUN6I_TCON0_LVDS_ANA0_C(2) |
> + SUN6I_TCON0_LVDS_ANA0_V(3) |
> + SUN6I_TCON0_LVDS_ANA0_PD(2) |
> + SUN6I_TCON0_LVDS_ANA0_EN_LDO);
> + udelay(2);
> +
> + regmap_update_bits(tcon->regs, SUN4I_TCON0_LVDS_ANA0_REG,
> + SUN6I_TCON0_LVDS_ANA0_EN_MB,
> + SUN6I_TCON0_LVDS_ANA0_EN_MB);
> + udelay(2);
> +
> + regmap_update_bits(tcon->regs, SUN4I_TCON0_LVDS_ANA0_REG,
> + SUN6I_TCON0_LVDS_ANA0_EN_DRVC,
> + SUN6I_TCON0_LVDS_ANA0_EN_DRVC);
> +
> + if (sun4i_tcon_get_pixel_depth(encoder) == 18)
> + val = 7;
> + else
> + val = 0xf;
> +
> + regmap_write_bits(tcon->regs, SUN4I_TCON0_LVDS_ANA0_REG,
> + SUN6I_TCON0_LVDS_ANA0_EN_DRVD(0xf),
> + SUN6I_TCON0_LVDS_ANA0_EN_DRVD(val));
> +
> +}
> +
> +static void sun4i_tcon_lvds_sun4i_enable(struct sun4i_tcon *tcon) {

And sun4i_tcon_setup_lvds_phy.

> + regmap_write(tcon->regs, SUN4I_TCON0_LVDS_ANA0_REG,
> + SUN4I_TCON0_LVDS_ANA0_CK_EN |
> + SUN4I_TCON0_LVDS_ANA0_REG_V |
> + SUN4I_TCON0_LVDS_ANA0_REG_C |
> + SUN4I_TCON0_LVDS_ANA0_EN_MB |
> + SUN4I_TCON0_LVDS_ANA0_PD |
> + SUN4I_TCON0_LVDS_ANA0_DCHS);
> +
> + udelay(2); /* delay at least 1200 ns */
> + regmap_update_bits(tcon->regs, SUN4I_TCON0_LVDS_ANA1_REG,
> + SUN4I_TCON0_LVDS_ANA1_INIT,
> + SUN4I_TCON0_LVDS_ANA1_INIT);
> + udelay(1); /* delay at least 1200 ns */

The delay and your comment don't match.

> + regmap_update_bits(tcon->regs, SUN4I_TCON0_LVDS_ANA1_REG,
> + SUN4I_TCON0_LVDS_ANA1_UPDATE,
> + SUN4I_TCON0_LVDS_ANA1_UPDATE);

You refer to U-Boot in your commit log, but the sequence is not quite
the same, why did you change it?

> +}
> +
> +
> static void sun4i_tcon_lvds_set_status(struct sun4i_tcon *tcon,
> const struct drm_encoder *encoder,
> bool enabled)
> {
> if (enabled) {
> - u8 val;
> -
> + // Enable LVDS interface

There's no need for that comment, it's simple enough :)

> regmap_update_bits(tcon->regs, SUN4I_TCON0_LVDS_IF_REG,
> SUN4I_TCON0_LVDS_IF_EN,
> SUN4I_TCON0_LVDS_IF_EN);
>
> - /*
> - * As their name suggest, these values only apply to the A31
> - * and later SoCs. We'll have to rework this when merging
> - * support for the older SoCs.
> - */
> - regmap_write(tcon->regs, SUN4I_TCON0_LVDS_ANA0_REG,
> - SUN6I_TCON0_LVDS_ANA0_C(2) |
> - SUN6I_TCON0_LVDS_ANA0_V(3) |
> - SUN6I_TCON0_LVDS_ANA0_PD(2) |
> - SUN6I_TCON0_LVDS_ANA0_EN_LDO);
> - udelay(2);
> -
> - regmap_update_bits(tcon->regs, SUN4I_TCON0_LVDS_ANA0_REG,
> - SUN6I_TCON0_LVDS_ANA0_EN_MB,
> - SUN6I_TCON0_LVDS_ANA0_EN_MB);
> - udelay(2);
> -
> - regmap_update_bits(tcon->regs, SUN4I_TCON0_LVDS_ANA0_REG,
> - SUN6I_TCON0_LVDS_ANA0_EN_DRVC,
> - SUN6I_TCON0_LVDS_ANA0_EN_DRVC);
> -
> - if (sun4i_tcon_get_pixel_depth(encoder) == 18)
> - val = 7;
> - else
> - val = 0xf;
> + // Perform SoC-specific setup procedure

Ditto.

> + if (tcon->quirks->sun6i_lvds_init) {
> + sun4i_tcon_lvds_sun6i_enable(tcon, encoder);
> + }
> + else {
> + sun4i_tcon_lvds_sun4i_enable(tcon);
> + }
>
> - regmap_write_bits(tcon->regs, SUN4I_TCON0_LVDS_ANA0_REG,
> - SUN6I_TCON0_LVDS_ANA0_EN_DRVD(0xf),
> - SUN6I_TCON0_LVDS_ANA0_EN_DRVD(val));
> } else {
> regmap_update_bits(tcon->regs, SUN4I_TCON0_LVDS_IF_REG,
> SUN4I_TCON0_LVDS_IF_EN, 0);
> @@ -1454,6 +1482,7 @@ static const struct sun4i_tcon_quirks sun6i_a31s_quirks = {
> };
>
> static const struct sun4i_tcon_quirks sun7i_a20_quirks = {
> + .supports_lvds = true,
> .has_channel_0 = true,
> .has_channel_1 = true,
> .dclk_min_div = 4,
> @@ -1464,11 +1493,13 @@ static const struct sun4i_tcon_quirks sun7i_a20_quirks = {
> static const struct sun4i_tcon_quirks sun8i_a33_quirks = {
> .has_channel_0 = true,
> .has_lvds_alt = true,
> + .sun6i_lvds_init = true,

Using a function pointer here (like we're doing with set_mux) would be
more future proof.

> .dclk_min_div = 1,
> };
>
> static const struct sun4i_tcon_quirks sun8i_a83t_lcd_quirks = {
> .supports_lvds = true,
> + .sun6i_lvds_init = true,
> .has_channel_0 = true,
> .dclk_min_div = 1,
> };
> diff --git a/drivers/gpu/drm/sun4i/sun4i_tcon.h b/drivers/gpu/drm/sun4i/sun4i_tcon.h
> index a62ec826ae71..973901c1bee5 100644
> --- a/drivers/gpu/drm/sun4i/sun4i_tcon.h
> +++ b/drivers/gpu/drm/sun4i/sun4i_tcon.h
> @@ -193,6 +193,13 @@
> #define SUN4I_TCON_MUX_CTRL_REG 0x200
>
> #define SUN4I_TCON0_LVDS_ANA0_REG 0x220
> +#define SUN4I_TCON0_LVDS_ANA0_DCHS BIT(16)
> +#define SUN4I_TCON0_LVDS_ANA0_PD BIT(20) | BIT(21)
> +#define SUN4I_TCON0_LVDS_ANA0_EN_MB BIT(22)
> +#define SUN4I_TCON0_LVDS_ANA0_REG_C BIT(24) | BIT(25)
> +#define SUN4I_TCON0_LVDS_ANA0_REG_V BIT(26) | BIT(27)
> +#define SUN4I_TCON0_LVDS_ANA0_CK_EN BIT(29) | BIT(28)
> +
> #define SUN6I_TCON0_LVDS_ANA0_EN_MB BIT(31)
> #define SUN6I_TCON0_LVDS_ANA0_EN_LDO BIT(30)
> #define SUN6I_TCON0_LVDS_ANA0_EN_DRVC BIT(24)
> @@ -201,6 +208,10 @@
> #define SUN6I_TCON0_LVDS_ANA0_V(x) (((x) & 3) << 8)
> #define SUN6I_TCON0_LVDS_ANA0_PD(x) (((x) & 3) << 4)
>
> +#define SUN4I_TCON0_LVDS_ANA1_REG 0x224
> +#define SUN4I_TCON0_LVDS_ANA1_INIT (0x1f << 26 | 0x1f << 10)
> +#define SUN4I_TCON0_LVDS_ANA1_UPDATE (0x1f << 16 | 0x1f << 00)

Having proper defines for those fields would be great too.

Side question, this will need some DT changes too, right?

Maxime
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