drm: mxsfb: Wrap FIFO reset and comments into mxsfb_reset_block()

Wrap FIFO reset and comments into mxsfb_reset_block(), this is a clean up.
No functional change.

Reviewed-by: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Alexander Stein <alexander.stein@ew.tq-group.com>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Lucas Stach <l.stach@pengutronix.de>
Cc: Peng Fan <peng.fan@nxp.com>
Cc: Robby Cai <robby.cai@nxp.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Stefan Agner <stefan@agner.ch>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20220417020800.336675-1-marex@denx.de

diff --git a/drivers/gpu/drm/mxsfb/mxsfb_kms.c b/drivers/gpu/drm/mxsfb/mxsfb_kms.c
index 4cfb6c0..45cabe0 100644 (file)
--- a/drivers/gpu/drm/mxsfb/mxsfb_kms.c
+++ b/drivers/gpu/drm/mxsfb/mxsfb_kms.c
@@ -191,6 +191,12 @@ static int mxsfb_reset_block(struct mxsfb_drm_private *mxsfb)
 {
        int ret;
 
+       /*
+        * It seems, you can't re-program the controller if it is still
+        * running. This may lead to shifted pictures (FIFO issue?), so
+        * first stop the controller and drain its FIFOs.
+        */
+
        ret = clear_poll_bit(mxsfb->base + LCDC_CTRL, CTRL_SFTRST);
        if (ret)
                return ret;
@@ -201,7 +207,20 @@ static int mxsfb_reset_block(struct mxsfb_drm_private *mxsfb)
        if (ret)
                return ret;
 
-       return clear_poll_bit(mxsfb->base + LCDC_CTRL, CTRL_CLKGATE);
+       ret = clear_poll_bit(mxsfb->base + LCDC_CTRL, CTRL_CLKGATE);
+       if (ret)
+               return ret;
+
+       /* Clear the FIFOs */
+       writel(CTRL1_FIFO_CLEAR, mxsfb->base + LCDC_CTRL1 + REG_SET);
+       readl(mxsfb->base + LCDC_CTRL1);
+       writel(CTRL1_FIFO_CLEAR, mxsfb->base + LCDC_CTRL1 + REG_CLR);
+       readl(mxsfb->base + LCDC_CTRL1);
+
+       if (mxsfb->devdata->has_overlay)
+               writel(0, mxsfb->base + LCDC_AS_CTRL);
+
+       return 0;
 }
 
 static dma_addr_t mxsfb_get_fb_paddr(struct drm_plane *plane)
@@ -228,26 +247,11 @@ static void mxsfb_crtc_mode_set_nofb(struct mxsfb_drm_private *mxsfb,
        u32 vdctrl0, vsync_pulse_len, hsync_pulse_len;
        int err;
 
-       /*
-        * It seems, you can't re-program the controller if it is still
-        * running. This may lead to shifted pictures (FIFO issue?), so
-        * first stop the controller and drain its FIFOs.
-        */
-
        /* Mandatory eLCDIF reset as per the Reference Manual */
        err = mxsfb_reset_block(mxsfb);
        if (err)
                return;
 
-       /* Clear the FIFOs */
-       writel(CTRL1_FIFO_CLEAR, mxsfb->base + LCDC_CTRL1 + REG_SET);
-       readl(mxsfb->base + LCDC_CTRL1);
-       writel(CTRL1_FIFO_CLEAR, mxsfb->base + LCDC_CTRL1 + REG_CLR);
-       readl(mxsfb->base + LCDC_CTRL1);
-
-       if (mxsfb->devdata->has_overlay)
-               writel(0, mxsfb->base + LCDC_AS_CTRL);
-
        mxsfb_set_formats(mxsfb, bus_format);
 
        clk_set_rate(mxsfb->clk, m->crtc_clock * 1000);