On 09/27/16 18:29, Bartosz Golaszewski wrote: > Some architectures don't use the common clock framework and don't > implement all the clk interfaces for every clock. This is the case > for da850-lcdk where clk_set_rate() only works for PLL0 and PLL1. > > Trying to set the clock rate for the LCDC clock results in -EINVAL > being returned. > > As a workaround for that: if the call to clk_set_rate() fails, fall > back to adjusting the clock divider instead. Proper divider value is > calculated by dividing the current clock rate by the required pixel > clock rate in HZ. > > This code is based on a hack initially developed internally for > baylibre by Karl Beldan <kbeldan@xxxxxxxxxxxx>. > > Tested with a da850-lcdk with an LCD display connected over VGA. > Could you rebase the fix on top of latest drm-next[1] (or my latest pull request tag[2])? The conflict is so big that it is better the check that the fix still works after rebasing. Best regards, Jyri [1] git://people.freedesktop.org/~airlied/linux drm-next [2] https://github.com/jsarha/linux tags/tilcdc-4.9-3.1 > Signed-off-by: Bartosz Golaszewski <bgolaszewski@xxxxxxxxxxxx> > --- > drivers/gpu/drm/tilcdc/tilcdc_crtc.c | 31 ++++++++++++++++++++++++------- > 1 file changed, 24 insertions(+), 7 deletions(-) > > diff --git a/drivers/gpu/drm/tilcdc/tilcdc_crtc.c b/drivers/gpu/drm/tilcdc/tilcdc_crtc.c > index 2087689..f2ff3b1 100644 > --- a/drivers/gpu/drm/tilcdc/tilcdc_crtc.c > +++ b/drivers/gpu/drm/tilcdc/tilcdc_crtc.c > @@ -636,22 +636,40 @@ void tilcdc_crtc_update_clk(struct drm_crtc *crtc) > struct drm_device *dev = crtc->dev; > struct tilcdc_drm_private *priv = dev->dev_private; > unsigned long lcd_clk; > - const unsigned clkdiv = 2; /* using a fixed divider of 2 */ > + unsigned int clkdiv; > int ret; > > pm_runtime_get_sync(dev->dev); > > tilcdc_crtc_disable(crtc); > > + clkdiv = 2; /* first try using a standard divider of 2 */ > + > /* mode.clock is in KHz, set_rate wants parameter in Hz */ > ret = clk_set_rate(priv->clk, crtc->mode.clock * 1000 * clkdiv); > + lcd_clk = clk_get_rate(priv->clk); > if (ret < 0) { > - dev_err(dev->dev, "failed to set display clock rate to: %d\n", > - crtc->mode.clock); > - goto out; > - } > + /* > + * If we fail to set the clock rate (some architectures don't > + * use the common clock framework yet and may not implement > + * all the clk API calls for every clock), try the next best > + * thing: adjusting the clock divider, unless clk_get_rate() > + * failed as well. > + */ > + dev_err(dev->dev, > + "failed to set display clock rate to: %d\n", > + crtc->mode.clock); > + if (!lcd_clk) { > + /* Nothing more we can do. Just bail out. */ > + dev_err(dev->dev, > + "failed to read the display clock rate\n"); > + goto out; > + } > > - lcd_clk = clk_get_rate(priv->clk); > + dev_info(dev->dev, > + "falling back to adjusting the clock divisor\n"); > + clkdiv = DIV_ROUND_CLOSEST(lcd_clk, (crtc->mode.clock * 1000)); > + } > > DBG("lcd_clk=%lu, mode clock=%d, div=%u", > lcd_clk, crtc->mode.clock, clkdiv); > @@ -664,7 +682,6 @@ void tilcdc_crtc_update_clk(struct drm_crtc *crtc) > tilcdc_set(dev, LCDC_CLK_ENABLE_REG, > LCDC_V2_DMA_CLK_EN | LCDC_V2_LIDD_CLK_EN | > LCDC_V2_CORE_CLK_EN); > - > if (tilcdc_crtc_is_on(crtc)) > tilcdc_crtc_enable(crtc); > > _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
