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| author | Linus Walleij <linus.walleij@linaro.org> | 2018-03-08 00:58:19 +0300 |
|---|---|---|
| committer | Linus Walleij <linus.walleij@linaro.org> | 2018-03-08 01:14:24 +0300 |
| commit | df99dd9202216f54eaf672e07808e9198d868af6 (patch) | |
| tree | ee75d257bc640dec1ff405deca483e83b63216e2 /drivers/gpu/drm/pl111/pl111_display.c | |
| parent | 2e7a66a8b5ebf1b04a866e5d7c981640f7f62934 (diff) | |
| download | linux-df99dd9202216f54eaf672e07808e9198d868af6.tar.xz | |
drm/pl111: Use max memory bandwidth for resolution
We were previously selecting 1024x768 and 32BPP as the default
set-up for the PL111 consumers.
This does not work on elder systems: the device tree bindings
support a property "max-memory-bandwidth" in bytes/second that
states that if you exceed this the memory bus will saturate.
The result is flickering and unstable images.
Parse the "max-memory-bandwidth" and respect it when
intializing the driver. On the RealView PB11MP, Versatile and
Integrator/CP we get a nice console as default with this code.
Reviewed-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20180307215819.15814-1-linus.walleij@linaro.org
Diffstat (limited to 'drivers/gpu/drm/pl111/pl111_display.c')
| -rw-r--r-- | drivers/gpu/drm/pl111/pl111_display.c | 36 |
1 files changed, 36 insertions, 0 deletions
diff --git a/drivers/gpu/drm/pl111/pl111_display.c b/drivers/gpu/drm/pl111/pl111_display.c index 5b8368c76734..310646427907 100644 --- a/drivers/gpu/drm/pl111/pl111_display.c +++ b/drivers/gpu/drm/pl111/pl111_display.c @@ -50,6 +50,41 @@ irqreturn_t pl111_irq(int irq, void *data) return status; } +static enum drm_mode_status +pl111_mode_valid(struct drm_crtc *crtc, + const struct drm_display_mode *mode) +{ + struct drm_device *drm = crtc->dev; + struct pl111_drm_dev_private *priv = drm->dev_private; + u32 cpp = priv->variant->fb_bpp / 8; + u64 bw; + + /* + * We use the pixelclock to also account for interlaced modes, the + * resulting bandwidth is in bytes per second. + */ + bw = mode->clock * 1000; /* In Hz */ + bw = bw * mode->hdisplay * mode->vdisplay * cpp; + bw = div_u64(bw, mode->htotal * mode->vtotal); + + /* + * If no bandwidth constraints, anything goes, else + * check if we are too fast. + */ + if (priv->memory_bw && (bw > priv->memory_bw)) { + DRM_DEBUG_KMS("%d x %d @ %d Hz, %d cpp, bw %llu too fast\n", + mode->hdisplay, mode->vdisplay, + mode->clock * 1000, cpp, bw); + + return MODE_BAD; + } + DRM_DEBUG_KMS("%d x %d @ %d Hz, %d cpp, bw %llu bytes/s OK\n", + mode->hdisplay, mode->vdisplay, + mode->clock * 1000, cpp, bw); + + return MODE_OK; +} + static int pl111_display_check(struct drm_simple_display_pipe *pipe, struct drm_plane_state *pstate, struct drm_crtc_state *cstate) @@ -348,6 +383,7 @@ static int pl111_display_prepare_fb(struct drm_simple_display_pipe *pipe, } static struct drm_simple_display_pipe_funcs pl111_display_funcs = { + .mode_valid = pl111_mode_valid, .check = pl111_display_check, .enable = pl111_display_enable, .disable = pl111_display_disable, |