[PATCH 5.14 058/169] drm/kmb: Work around for higher system clock

Greg Kroah-Hartman
2021-10-25T19:48:37Z

From: Anitha Chrisanthus <anitha.chrisanthus@intel.com>

[ Upstream commit 3e4c31e8f70251732529a10934355084c7fab0ac ]

Use a different value for system clock offset in the
ppl/llp ratio calculations for clocks higher than 500 Mhz.

Fixes: 98521f4d4b4c ("drm/kmb: Mipi DSI part of the display driver")
Signed-off-by: Anitha Chrisanthus <anitha.chrisanthus@intel.com>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20211013233632.471892-1-anitha.chrisanthus@intel.com
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/gpu/drm/kmb/kmb_dsi.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/kmb/kmb_dsi.c b/drivers/gpu/drm/kmb/kmb_dsi.c
index 231041b269f5..7e2371ffcb18 100644
--- a/drivers/gpu/drm/kmb/kmb_dsi.c
+++ b/drivers/gpu/drm/kmb/kmb_dsi.c
@@ -482,6 +482,10 @@ static u32 mipi_tx_fg_section_cfg(struct kmb_dsi *kmb_dsi,
return 0;
}

+#define CLK_DIFF_LOW 50
+#define CLK_DIFF_HI 60
+#define SYSCLK_500 500
+
static void mipi_tx_fg_cfg_regs(struct kmb_dsi *kmb_dsi, u8 frame_gen,
struct mipi_tx_frame_timing_cfg *fg_cfg)
{
@@ -492,7 +496,12 @@ static void mipi_tx_fg_cfg_regs(struct kmb_dsi *kmb_dsi, u8 frame_gen,
/* 500 Mhz system clock minus 50 to account for the difference in
* MIPI clock speed in RTL tests
*/
- sysclk = kmb_dsi->sys_clk_mhz - 50;
+ if (kmb_dsi->sys_clk_mhz == SYSCLK_500) {
+ sysclk = kmb_dsi->sys_clk_mhz - CLK_DIFF_LOW;
+ } else {
+ /* 700 Mhz clk*/
+ sysclk = kmb_dsi->sys_clk_mhz - CLK_DIFF_HI;
+ }

/* PPL-Pixel Packing Layer, LLP-Low Level Protocol
* Frame genartor timing parameters are clocked on the system clock,
--
2.33.0