Hi Joel,
> -----Original Message-----
> From: Joel Stanley <joel@xxxxxxxxx>
> Sent: Tuesday, April 26, 2022 11:27 AM
> To: Tommy Huang <tommy_huang@xxxxxxxxxxxxxx>
> Cc: David Airlie <airlied@xxxxxxxx>; Daniel Vetter <daniel@xxxxxxxx>; Rob
> Herring <robh+dt@xxxxxxxxxx>; Andrew Jeffery <andrew@xxxxxxxx>;
> linux-aspeed <linux-aspeed@xxxxxxxxxxxxxxxx>; open list:DRM DRIVERS
> <dri-devel@xxxxxxxxxxxxxxxxxxxxx>; devicetree <devicetree@xxxxxxxxxxxxxxx>;
> Linux ARM <linux-arm-kernel@xxxxxxxxxxxxxxxxxxx>; Linux Kernel Mailing List
> <linux-kernel@xxxxxxxxxxxxxxx>; BMC-SW <BMC-SW@xxxxxxxxxxxxxx>
> Subject: Re: [PATCH v1 2/2] drm/aspeed: Add 1024x768 mode for AST2600
>
> On Fri, 4 Mar 2022 at 06:32, Tommy Haung <tommy_huang@xxxxxxxxxxxxxx>
> wrote:
> >
> > Update the aspeed_gfx_set_clk with display width.
> > At AST2600, the display clock could be coming from HPLL clock / 16 =
> > 75MHz. It would fit 1024x768@70Hz.
> > Another chip will still keep 800x600.
> >
> > Signed-off-by: Tommy Haung <tommy_huang@xxxxxxxxxxxxxx>
> > ---
> > drivers/gpu/drm/aspeed/aspeed_gfx.h | 12 ++++++----
> > drivers/gpu/drm/aspeed/aspeed_gfx_crtc.c | 29
> > ++++++++++++++++++++---- drivers/gpu/drm/aspeed/aspeed_gfx_drv.c |
> > 16 +++++++++++-- drivers/gpu/drm/aspeed/aspeed_gfx_out.c | 14
> > +++++++++++-
> > 4 files changed, 60 insertions(+), 11 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/aspeed/aspeed_gfx.h
> > b/drivers/gpu/drm/aspeed/aspeed_gfx.h
> > index eb4c267cde5e..c7aefee0657a 100644
> > --- a/drivers/gpu/drm/aspeed/aspeed_gfx.h
> > +++ b/drivers/gpu/drm/aspeed/aspeed_gfx.h
> > @@ -109,11 +109,15 @@ int aspeed_gfx_create_output(struct drm_device
> *drm);
> > #define CRT_THROD_HIGH(x) ((x) << 8)
> >
> > /* SCU control */
> > -#define SCU_G6_CLK_COURCE 0x300
> > +#define G6_CLK_SOURCE 0x300
> > +#define G6_CLK_SOURCE_MASK (BIT(8) | BIT(9) | BIT(10))
> > +#define G6_CLK_SOURCE_HPLL (BIT(8) | BIT(9) | BIT(10))
> > +#define G6_CLK_SOURCE_USB BIT(9)
> > +#define G6_CLK_SEL3 0x308
> > +#define G6_CLK_DIV_MASK 0x3F000
> > +#define G6_CLK_DIV_16
> (BIT(16)|BIT(15)|BIT(13)|BIT(12))
> > +#define G6_USB_40_CLK BIT(9)
> >
> > /* GFX FLAGS */
> > #define CLK_MASK BIT(0)
> > #define CLK_G6 BIT(0)
> > -
> > -#define G6_CLK_MASK (BIT(8) | BIT(9) | BIT(10))
> > -#define G6_USB_40_CLK BIT(9)
> > diff --git a/drivers/gpu/drm/aspeed/aspeed_gfx_crtc.c
> > b/drivers/gpu/drm/aspeed/aspeed_gfx_crtc.c
> > index a24fab22eac4..5829be9c7c67 100644
> > --- a/drivers/gpu/drm/aspeed/aspeed_gfx_crtc.c
> > +++ b/drivers/gpu/drm/aspeed/aspeed_gfx_crtc.c
> > @@ -23,6 +23,28 @@ drm_pipe_to_aspeed_gfx(struct
> drm_simple_display_pipe *pipe)
> > return container_of(pipe, struct aspeed_gfx, pipe); }
> >
> > +static void aspeed_gfx_set_clock_source(struct aspeed_gfx *priv, int
> > +mode_width) {
> > + regmap_update_bits(priv->scu, G6_CLK_SOURCE,
> G6_CLK_SOURCE_MASK, 0x0);
> > + regmap_update_bits(priv->scu, G6_CLK_SEL3, G6_CLK_DIV_MASK,
> > +0x0);
> > +
> > + switch (mode_width) {
> > + case 1024:
> > + /* hpll div 16 = 75Mhz */
> > + regmap_update_bits(priv->scu, G6_CLK_SOURCE,
> > + G6_CLK_SOURCE_MASK, G6_CLK_SOURCE_HPLL);
> > + regmap_update_bits(priv->scu, G6_CLK_SEL3,
> > + G6_CLK_DIV_MASK, G6_CLK_DIV_16);
> > + break;
> > + case 800:
> > + default:
> > + /* usb 40Mhz */
> > + regmap_update_bits(priv->scu, G6_CLK_SOURCE,
> > + G6_CLK_SOURCE_MASK, G6_CLK_SOURCE_USB);
> > + break;
> > + }
>
> I'm not familiar with this area, but I think this belongs in the clock driver.
>
> We want to be able to call clk_set_rate() from the drm driver and have the
> clock driver update the correct bits in the SCU.
>
> Instead of specialising the 2600 vs others, could clk_set_rate() fail on the
> others, and cause the driver to stay at 800x600. If the set succeeds it can then
> run at the higher resolution. If this is not how the APIs work, we could instead
> have a clock_rate in struct aspeed_gfx and each platform can define its
> expected clock rate. It would then need a corresponding resolution.
>
> Please take a look at other drivers and see what they do.
Thanks for your common. The pixel clock selection is very limit on soc display.
Until now, there are just two resolutions (800x600@60 and 1024x768@70)could be selected at ast2600.
And there is just 800x600@60 could be selected at ast2500 and ast2400.
Although I also want to have clk_set_rate() function to select flexible pixel clock with a programable pll.
We might define support clock rate in every device structure for this situation.
>
>
>
> > +}
> > +
> > static int aspeed_gfx_set_pixel_fmt(struct aspeed_gfx *priv, u32
> > *bpp) {
> > struct drm_crtc *crtc = &priv->pipe.crtc; @@ -77,12 +99,11 @@
> > static void aspeed_gfx_disable_controller(struct aspeed_gfx *priv)
> > regmap_update_bits(priv->scu, priv->dac_reg, BIT(16), 0); }
> >
> > -static void aspeed_gfx_set_clk(struct aspeed_gfx *priv)
> > +static void aspeed_gfx_set_clk(struct aspeed_gfx *priv, int
> > +mode_width)
> > {
> > switch (priv->flags & CLK_MASK) {
> > case CLK_G6:
> > - regmap_update_bits(priv->scu, SCU_G6_CLK_COURCE,
> G6_CLK_MASK, 0x0);
> > - regmap_update_bits(priv->scu, SCU_G6_CLK_COURCE,
> G6_CLK_MASK, G6_USB_40_CLK);
> > + aspeed_gfx_set_clock_source(priv, mode_width);
> > break;
> > default:
> > break;
> > @@ -99,7 +120,7 @@ static void aspeed_gfx_crtc_mode_set_nofb(struct
> aspeed_gfx *priv)
> > if (err)
> > return;
> >
> > - aspeed_gfx_set_clk(priv);
> > + aspeed_gfx_set_clk(priv, m->hdisplay);
> >
> > #if 0
> > /* TODO: we have only been able to test with the 40MHz USB
> > clock. The diff --git a/drivers/gpu/drm/aspeed/aspeed_gfx_drv.c
> > b/drivers/gpu/drm/aspeed/aspeed_gfx_drv.c
> > index af56ffdccc65..e1a814aebc2d 100644
> > --- a/drivers/gpu/drm/aspeed/aspeed_gfx_drv.c
> > +++ b/drivers/gpu/drm/aspeed/aspeed_gfx_drv.c
> > @@ -110,6 +110,7 @@ static const struct drm_mode_config_funcs
> > aspeed_gfx_mode_config_funcs = {
> >
> > static int aspeed_gfx_setup_mode_config(struct drm_device *drm) {
> > + struct aspeed_gfx *priv = to_aspeed_gfx(drm);
> > int ret;
> >
> > ret = drmm_mode_config_init(drm); @@ -118,8 +119,18 @@
> static
> > int aspeed_gfx_setup_mode_config(struct drm_device *drm)
> >
> > drm->mode_config.min_width = 0;
> > drm->mode_config.min_height = 0;
> > - drm->mode_config.max_width = 800;
> > - drm->mode_config.max_height = 600;
> > +
> > + switch (priv->flags & CLK_MASK) {
> > + case CLK_G6:
> > + drm->mode_config.max_width = 1024;
> > + drm->mode_config.max_height = 768;
> > + break;
> > + default:
> > + drm->mode_config.max_width = 800;
> > + drm->mode_config.max_height = 600;
> > + break;
> > + }
> > +
> > drm->mode_config.funcs = &aspeed_gfx_mode_config_funcs;
> >
> > return ret;
> > @@ -167,6 +178,7 @@ static int aspeed_gfx_load(struct drm_device *drm)
> > priv->vga_scratch_reg = config->vga_scratch_reg;
> > priv->throd_val = config->throd_val;
> > priv->scan_line_max = config->scan_line_max;
> > + priv->flags = config->gfx_flags;
> >
> > priv->scu = syscon_regmap_lookup_by_phandle(np, "syscon");
> > if (IS_ERR(priv->scu)) {
> > diff --git a/drivers/gpu/drm/aspeed/aspeed_gfx_out.c
> > b/drivers/gpu/drm/aspeed/aspeed_gfx_out.c
> > index 6759cb88415a..5d5e04f15c59 100644
> > --- a/drivers/gpu/drm/aspeed/aspeed_gfx_out.c
> > +++ b/drivers/gpu/drm/aspeed/aspeed_gfx_out.c
> > @@ -10,7 +10,19 @@
> >
> > static int aspeed_gfx_get_modes(struct drm_connector *connector) {
> > - return drm_add_modes_noedid(connector, 800, 600);
> > + struct aspeed_gfx *priv = container_of(connector, struct
> aspeed_gfx, connector);
> > + int mode_count = 0;
> > +
> > + switch (priv->flags & CLK_MASK) {
> > + case CLK_G6:
> > + mode_count = drm_add_modes_noedid(connector, 1024,
> 768);
> > + break;
> > + default:
> > + mode_count = drm_add_modes_noedid(connector, 800,
> 600);
> > + break;
> > + }
> > +
> > + return mode_count;
> > }
> >
> > static const struct
> > --
> > 2.17.1
> >
