On 04/03/15 09:06, Liu Ying wrote: > The LCDIF engines embedded in i.MX6sl and i.MX6sx SoCs need the axi clock > as the engine's system clock. The clock should be enabled when accessing > LCDIF registers, otherwise the kernel would hang up. We should also keep > the clock being enabled when the engine is being active to scan out frames
The text above is a bit confusing. Maybe just "... also keep the clock enabled when..." > from memory. This patch makes sure the axi clock is enabled when accessing > registers so that the kernel hang up issue can be fixed. > > Reported-by: Peter Chen <[email protected]> > Tested-by: Peter Chen <[email protected]> > Cc: <[email protected]> # 3.19+ > Signed-off-by: Liu Ying <[email protected]> > --- > v1->v2: > * Add 'Tested-by: Peter Chen <[email protected]>' tag. > * Add 'Cc: <[email protected]> # 3.19+' tag. > > drivers/video/fbdev/mxsfb.c | 70 > ++++++++++++++++++++++++++++++++++++--------- > 1 file changed, 56 insertions(+), 14 deletions(-) > > diff --git a/drivers/video/fbdev/mxsfb.c b/drivers/video/fbdev/mxsfb.c > index f8ac4a4..a8cf3b2 100644 > --- a/drivers/video/fbdev/mxsfb.c > +++ b/drivers/video/fbdev/mxsfb.c > @@ -316,6 +316,18 @@ static int mxsfb_check_var(struct fb_var_screeninfo *var, > return 0; > } > > +static inline void mxsfb_enable_axi_clk(struct mxsfb_info *host) > +{ > + if (host->clk_axi) > + clk_prepare_enable(host->clk_axi); > +} > + > +static inline void mxsfb_disable_axi_clk(struct mxsfb_info *host) > +{ > + if (host->clk_axi) > + clk_disable_unprepare(host->clk_axi); > +} > + > static void mxsfb_enable_controller(struct fb_info *fb_info) > { > struct mxsfb_info *host = to_imxfb_host(fb_info); > @@ -333,14 +345,13 @@ static void mxsfb_enable_controller(struct fb_info > *fb_info) > } > } > > - if (host->clk_axi) > - clk_prepare_enable(host->clk_axi); > - > if (host->clk_disp_axi) > clk_prepare_enable(host->clk_disp_axi); > clk_prepare_enable(host->clk); > clk_set_rate(host->clk, PICOS2KHZ(fb_info->var.pixclock) * 1000U); > > + mxsfb_enable_axi_clk(host); > + Is there some reason to move the clk enable to a different place here? > /* if it was disabled, re-enable the mode again */ > writel(CTRL_DOTCLK_MODE, host->base + LCDC_CTRL + REG_SET); > > @@ -380,11 +391,11 @@ static void mxsfb_disable_controller(struct fb_info > *fb_info) > reg = readl(host->base + LCDC_VDCTRL4); > writel(reg & ~VDCTRL4_SYNC_SIGNALS_ON, host->base + LCDC_VDCTRL4); > > + mxsfb_disable_axi_clk(host); > + > clk_disable_unprepare(host->clk); > if (host->clk_disp_axi) > clk_disable_unprepare(host->clk_disp_axi); > - if (host->clk_axi) > - clk_disable_unprepare(host->clk_axi); And same here for disable. > host->enabled = 0; > > @@ -421,6 +432,8 @@ static int mxsfb_set_par(struct fb_info *fb_info) > mxsfb_disable_controller(fb_info); > } > > + mxsfb_enable_axi_clk(host); > + > /* clear the FIFOs */ > writel(CTRL1_FIFO_CLEAR, host->base + LCDC_CTRL1 + REG_SET); > > @@ -438,6 +451,7 @@ static int mxsfb_set_par(struct fb_info *fb_info) > ctrl |= CTRL_SET_WORD_LENGTH(3); > switch (host->ld_intf_width) { > case STMLCDIF_8BIT: > + mxsfb_disable_axi_clk(host); > dev_err(&host->pdev->dev, > "Unsupported LCD bus width mapping\n"); > return -EINVAL; > @@ -451,6 +465,7 @@ static int mxsfb_set_par(struct fb_info *fb_info) > writel(CTRL1_SET_BYTE_PACKAGING(0x7), host->base + LCDC_CTRL1); > break; > default: > + mxsfb_disable_axi_clk(host); > dev_err(&host->pdev->dev, "Unhandled color depth of %u\n", > fb_info->var.bits_per_pixel); > return -EINVAL; > @@ -504,6 +519,8 @@ static int mxsfb_set_par(struct fb_info *fb_info) > fb_info->fix.line_length * fb_info->var.yoffset, > host->base + host->devdata->next_buf); > > + mxsfb_disable_axi_clk(host); > + > if (reenable) > mxsfb_enable_controller(fb_info); > > @@ -582,10 +599,16 @@ static int mxsfb_pan_display(struct fb_var_screeninfo > *var, > > offset = fb_info->fix.line_length * var->yoffset; > > + if (!host->enabled) > + mxsfb_enable_axi_clk(host); > + > /* update on next VSYNC */ > writel(fb_info->fix.smem_start + offset, > host->base + host->devdata->next_buf); > > + if (!host->enabled) > + mxsfb_disable_axi_clk(host); > + Why do you check for host->enabled here, but not elsewhere? Tomi
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