linux-kernel - Re: [PATCH v2 2/3] drm/sun4i: use drm_mode_validate

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Message-ID: <CAGb2v64kH6gWRjBxHcFKw++vx9G7dwoiRCz0heaLO786orvd4w@mail.gmail.com>
Date: Tue, 26 Nov 2024 00:10:42 +0800
From: Chen-Yu Tsai <wens@...e.org>
To: Sean Nyekjaer <sean@...nix.com>
Cc: Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, Maxime Ripard <mripard@...nel.org>, 
	Thomas Zimmermann <tzimmermann@...e.de>, David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>, 
	Jernej Skrabec <jernej.skrabec@...il.com>, Samuel Holland <samuel@...lland.org>, 
	Yannick Fertre <yannick.fertre@...s.st.com>, 
	Raphael Gallais-Pou <raphael.gallais-pou@...s.st.com>, 
	Philippe Cornu <philippe.cornu@...s.st.com>, Maxime Coquelin <mcoquelin.stm32@...il.com>, 
	Alexandre Torgue <alexandre.torgue@...s.st.com>, dri-devel@...ts.freedesktop.org, 
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, 
	linux-sunxi@...ts.linux.dev, linux-stm32@...md-mailman.stormreply.com
Subject: Re: [PATCH v2 2/3] drm/sun4i: use drm_mode_validate_mode() helper function

On Mon, Nov 25, 2024 at 9:50 PM Sean Nyekjaer <sean@...nix.com> wrote:
>
> Use new helper function for HDMI mode validation

This is a bit misleading since this is actually the DPI or parallel
output encoder, not HDMI. HDMI is in drivers/gpu/drm/sun4i/sun4i_hdmi_enc.c
and drivers/gpu/drm/sun4i/sun8i_dw_hdmi.c

ChenYu

> Signed-off-by: Sean Nyekjaer <sean@...nix.com>
> ---
>  drivers/gpu/drm/sun4i/sun4i_rgb.c | 22 ++++------------------
>  1 file changed, 4 insertions(+), 18 deletions(-)
>
> diff --git a/drivers/gpu/drm/sun4i/sun4i_rgb.c b/drivers/gpu/drm/sun4i/sun4i_rgb.c
> index dfb6acc42f02efc40f36914e2925510cd8056d0b..4f8100e32769cf31c25f5dd849a18f5b77376090 100644
> --- a/drivers/gpu/drm/sun4i/sun4i_rgb.c
> +++ b/drivers/gpu/drm/sun4i/sun4i_rgb.c
> @@ -51,14 +51,6 @@ static int sun4i_rgb_get_modes(struct drm_connector *connector)
>         return drm_panel_get_modes(rgb->panel, connector);
>  }
>
> -/*
> - * VESA DMT defines a tolerance of 0.5% on the pixel clock, while the
> - * CVT spec reuses that tolerance in its examples, so it looks to be a
> - * good default tolerance for the EDID-based modes. Define it to 5 per
> - * mille to avoid floating point operations.
> - */
> -#define SUN4I_RGB_DOTCLOCK_TOLERANCE_PER_MILLE 5
> -
>  static enum drm_mode_status sun4i_rgb_mode_valid(struct drm_encoder *crtc,
>                                                  const struct drm_display_mode *mode)
>  {
> @@ -67,8 +59,8 @@ static enum drm_mode_status sun4i_rgb_mode_valid(struct drm_encoder *crtc,
>         u32 hsync = mode->hsync_end - mode->hsync_start;
>         u32 vsync = mode->vsync_end - mode->vsync_start;
>         unsigned long long rate = mode->clock * 1000;
> -       unsigned long long lowest, highest;
>         unsigned long long rounded_rate;
> +       int ret;
>
>         DRM_DEBUG_DRIVER("Validating modes...\n");
>
> @@ -122,15 +114,9 @@ static enum drm_mode_status sun4i_rgb_mode_valid(struct drm_encoder *crtc,
>         tcon->dclk_max_div = 127;
>         rounded_rate = clk_round_rate(tcon->dclk, rate);
>
> -       lowest = rate * (1000 - SUN4I_RGB_DOTCLOCK_TOLERANCE_PER_MILLE);
> -       do_div(lowest, 1000);
> -       if (rounded_rate < lowest)
> -               return MODE_CLOCK_LOW;
> -
> -       highest = rate * (1000 + SUN4I_RGB_DOTCLOCK_TOLERANCE_PER_MILLE);
> -       do_div(highest, 1000);
> -       if (rounded_rate > highest)
> -               return MODE_CLOCK_HIGH;
> +       ret = drm_mode_validate_mode(mode, rounded_rate);
> +       if (ret)
> +               return ret;
>
>  out:
>         DRM_DEBUG_DRIVER("Clock rate OK\n");
>
> --
> 2.46.2
>
>