media: camss: use v4l2_get_link_freq() to calculate the relevant clocks

There are places in the camss driver where camss_get_pixel_clock() is
called to get the pixel rate (using V4L2_CID_PIXEL_RATE control) and to
calculate the link frequency from it. There is a case when this would
not work: when V4L2_CID_PIXEL_RATE gets the rate at which the pixels are
read (sampled) from the sensor's pixel array, and this rate is different
from the pixel transmission rate over the CSI link, the link frequency
value can't be calculated from the pixel rate. One needs to use
V4L2_CID_LINK_FREQ to get the link frequency in this case.

Replace such calls to camss_get_pixel_clock() with calls to a wrapper
around v4l2_get_link_freq(). v4l2_get_link_freq() tries V4L2_CID_LINK_FREQ
first, and if it is not implemented by the camera sensor driver, falls
back to V4L2_CID_PIXEL_RATE to calculate the link frequency value from.

Calls to camss_get_pixel_clock() from vfe_[check,set]_clock_rates()
are left intact as it looks like this VFE clock does depend on the
rate the pixel samples comes out of the camera sensor, not on the
frequency at which the link between the sensor and the CSI receiver
operates.

Signed-off-by: Andrey Konovalov <andrey.konovalov@linaro.org>
Acked-by: Robert Foss <robert.foss@linaro.org>
Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

1 files changed, 10 insertions, 12 deletions

diff --git a/drivers/media/platform/qcom/camss/camss-csiphy-2ph-1-0.c b/drivers/media/platform/qcom/camss/camss-csiphy-2ph-1-0.c
index 12bce391d71f..30b454c369ab 100644
--- a/drivers/media/platform/qcom/camss/camss-csiphy-2ph-1-0.c
+++ b/drivers/media/platform/qcom/camss/camss-csiphy-2ph-1-0.c
@@ -51,16 +51,13 @@ static void csiphy_reset(struct csiphy_device *csiphy)
  *
  * Helper function to calculate settle count value. This is
  * based on the CSI2 T_hs_settle parameter which in turn
- * is calculated based on the CSI2 transmitter pixel clock
- * frequency.
+ * is calculated based on the CSI2 transmitter link frequency.
  *
- * Return settle count value or 0 if the CSI2 pixel clock
- * frequency is not available
+ * Return settle count value or 0 if the CSI2 link frequency
+ * is not available
  */
-static u8 csiphy_settle_cnt_calc(u32 pixel_clock, u8 bpp, u8 num_lanes,
-				 u32 timer_clk_rate)
+static u8 csiphy_settle_cnt_calc(s64 link_freq, u32 timer_clk_rate)
 {
-	u32 mipi_clock; /* Hz */
 	u32 ui; /* ps */
 	u32 timer_period; /* ps */
 	u32 t_hs_prepare_max; /* ps */
@@ -68,8 +65,10 @@ static u8 csiphy_settle_cnt_calc(u32 pixel_clock, u8 bpp, u8 num_lanes,
 	u32 t_hs_settle; /* ps */
 	u8 settle_cnt;
 
-	mipi_clock = pixel_clock * bpp / (2 * num_lanes);
-	ui = div_u64(1000000000000LL, mipi_clock);
+	if (link_freq <= 0)
+		return 0;
+
+	ui = div_u64(1000000000000LL, link_freq);
 	ui /= 2;
 	t_hs_prepare_max = 85000 + 6 * ui;
 	t_hs_prepare_zero_min = 145000 + 10 * ui;
@@ -83,15 +82,14 @@ static u8 csiphy_settle_cnt_calc(u32 pixel_clock, u8 bpp, u8 num_lanes,
 
 static void csiphy_lanes_enable(struct csiphy_device *csiphy,
 				struct csiphy_config *cfg,
-				u32 pixel_clock, u8 bpp, u8 lane_mask)
+				s64 link_freq, u8 lane_mask)
 {
 	struct csiphy_lanes_cfg *c = &cfg->csi2->lane_cfg;
 	u8 settle_cnt;
 	u8 val, l = 0;
 	int i = 0;
 
-	settle_cnt = csiphy_settle_cnt_calc(pixel_clock, bpp, c->num_data,
-					    csiphy->timer_clk_rate);
+	settle_cnt = csiphy_settle_cnt_calc(link_freq, csiphy->timer_clk_rate);
 
 	writel_relaxed(0x1, csiphy->base +
 		       CAMSS_CSI_PHY_GLBL_T_INIT_CFG0);