ARM HDLCD: Fix clock initialisation sequence

This reworks HDLCD initialisation to mirror how CLCD does this, in
particular to prepare the clock immediately after it has been got which
ensures that we don't try and enable clocks before they were prepared,
e.g. in the former clk_enable after register_framebuffer().

The reason this issue wasn't noticed before is that we have been
setting CONFIG_FRAMEBUFFER_CONSOLE and this caused
register_framebuffer() to trigger the creation of a console which calls
hdlcd_set_par(), which in turn was preparing and enabling the clock.

Signed-off-by: Jon Medhurst <tixy@linaro.org>

diff --git a/drivers/video/arm-hdlcd.c b/drivers/video/arm-hdlcd.c
index f9c4e7490c0517005c85ed45586d4a6b5028dfdc..cfd631e3dc5224abbf3297e194edc5348a0aebb1 100644 (file)
--- a/drivers/video/arm-hdlcd.c
+++ b/drivers/video/arm-hdlcd.c
@@ -289,7 +289,6 @@ static int hdlcd_set_par(struct fb_info *info)
        WRITE_HDLCD_REG(HDLCD_REG_GREEN_SELECT, ((hdlcd->fb.var.green.length & 0xf) << 8) | hdlcd->fb.var.green.offset);
        WRITE_HDLCD_REG(HDLCD_REG_BLUE_SELECT, ((hdlcd->fb.var.blue.length & 0xf) << 8) | hdlcd->fb.var.blue.offset);
 
-       clk_prepare(hdlcd->clk);
        clk_set_rate(hdlcd->clk, (1000000000 / hdlcd->fb.var.pixclock) * 1000);
        clk_enable(hdlcd->clk);
 
@@ -481,6 +480,10 @@ static int hdlcd_setup(struct hdlcd_device *hdlcd)
                return PTR_ERR(hdlcd->clk);
        }
 
+       err = clk_prepare(hdlcd->clk);
+       if (err)
+               goto clk_prepare_err;
+
        hdlcd->base = ioremap_nocache(hdlcd->fb.fix.mmio_start, hdlcd->fb.fix.mmio_len);
        if (!hdlcd->base) {
                dev_err(hdlcd->dev, "HDLCD: unable to map registers\n");
@@ -572,9 +575,9 @@ static int hdlcd_setup(struct hdlcd_device *hdlcd)
        /* Ensure interrupts are disabled */
        WRITE_HDLCD_REG(HDLCD_REG_INT_MASK, 0);
 #endif 
+       fb_set_var(&hdlcd->fb, &hdlcd->fb.var);
+
        if (!register_framebuffer(&hdlcd->fb)) {
-               fb_set_var(&hdlcd->fb, &hdlcd->fb.var);
-               clk_enable(hdlcd->clk);
                return 0;
        }
 
@@ -586,6 +589,8 @@ setup_err:
 kmalloc_err:
        kfree(hdlcd->fb.pseudo_palette);
 remap_err:
+       clk_unprepare(hdlcd->clk);
+clk_prepare_err:
        clk_put(hdlcd->clk);
        return err;
 }