[PATCH 3/3] fbdev: simplefb: Use __clk_disable_unprepare_counts_only()

[Hans de Goede <johannes.goede@oss.qualcomm.com>]

simplefb_clocks_enable() calls clk_prepare_enable() to avoid clocks used by
the framebuffer getting turned off while in use.

This requires simplefb_clocks_destroy() calling clk_disable_unprepare() to
balance the enable count. clk_disable_unprepare() actually turns the clock
off, messing with the hardware state before the real display driver loads,
without any knowledge of the proper display power-off sequence.

Sometimes this leaves the hardware in an undefined state e.g. on some
Qualcomm platforms turning off the DP clocks at simplefb_destroy() results
in the following error when the msm display driver tries to re-enable them:

[    2.980181] disp_cc_mdss_dptx3_pixel0_clk_src: rcg didn't update its configuration.
[    2.980272] WARNING: drivers/clk/qcom/clk-rcg2.c:136 at update_config+0xdc/0x100

Resulting in a non work display output.

Switch to using the new __clk_disable_unprepare_counts_only() function,
which decrements the counts without actually turning off the clocks.

Signed-off-by: Hans de Goede <johannes.goede@oss.qualcomm.com>
---
 drivers/video/fbdev/simplefb.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/video/fbdev/simplefb.c b/drivers/video/fbdev/simplefb.c
index 60e5dcec201f..b1e0dba6d127 100644
--- a/drivers/video/fbdev/simplefb.c
+++ b/drivers/video/fbdev/simplefb.c
@@ -303,7 +303,7 @@ static void simplefb_clocks_destroy(struct simplefb_par *par)
 	for (i = 0; i < par->clk_count; i++) {
 		if (par->clks[i]) {
 			if (par->clks_enabled)
-				clk_disable_unprepare(par->clks[i]);
+				__clk_disable_unprepare_counts_only(par->clks[i]);
 			clk_put(par->clks[i]);
 		}
 	}
-- 
2.54.0