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, 9 insertions, 11 deletions

diff --git a/drivers/media/platform/qcom/camss/camss-csid.c b/drivers/media/platform/qcom/camss/camss-csid.c
index be3fe76f3dc3..cff9759c9158 100644
--- a/drivers/media/platform/qcom/camss/camss-csid.c
+++ b/drivers/media/platform/qcom/camss/camss-csid.c
@@ -462,13 +462,17 @@ static irqreturn_t csid_isr(int irq, void *dev)
 static int csid_set_clock_rates(struct csid_device *csid)
 {
 	struct device *dev = csid->camss->dev;
-	u32 pixel_clock;
+	const struct csid_format *fmt;
+	s64 link_freq;
 	int i, j;
 	int ret;
 
-	ret = camss_get_pixel_clock(&csid->subdev.entity, &pixel_clock);
-	if (ret)
-		pixel_clock = 0;
+	fmt = csid_get_fmt_entry(csid->formats, csid->nformats,
+				 csid->fmt[MSM_CSIPHY_PAD_SINK].code);
+	link_freq = camss_get_link_freq(&csid->subdev.entity, fmt->bpp,
+					csid->phy.lane_cnt);
+	if (link_freq < 0)
+		link_freq = 0;
 
 	for (i = 0; i < csid->nclocks; i++) {
 		struct camss_clock *clock = &csid->clock[i];
@@ -477,13 +481,7 @@ static int csid_set_clock_rates(struct csid_device *csid)
 		    !strcmp(clock->name, "csi1") ||
 		    !strcmp(clock->name, "csi2") ||
 		    !strcmp(clock->name, "csi3")) {
-			const struct csid_format *f = csid_get_fmt_entry(
-				csid->formats,
-				csid->nformats,
-				csid->fmt[MSM_CSIPHY_PAD_SINK].code);
-			u8 num_lanes = csid->phy.lane_cnt;
-			u64 min_rate = pixel_clock * f->bpp /
-							(2 * num_lanes * 4);
+			u64 min_rate = link_freq / 4;
 			long rate;
 
 			camss_add_clock_margin(&min_rate);