[PATCH v4 2/6] media: qcom: camss: clamp VFE clock rates to the highest level

[Atanas Filipov]

The VFE fails to power on when the pixel rate exceeds the highest rate
listed for any of its clocks. The rate tables of the VFE clocks are
independent and need not have the same number of levels, so a clock
with a lower top rate than the VFE core clock, such as the SC7280
camnoc_axi clock, makes the VFE reject pixel rates the core clock
still supports.

Keep failing when the pixel rate exceeds the highest rate of the VFE
core clock, and clamp the other VFE clocks to their highest listed
rate instead. Take the clamp into account for the other clocks when
another line powers on an already running VFE, so that a clock
running at its highest rate does not reject the request.

Signed-off-by: Atanas Filipov <atanas.filipov@xxxxxxxxxxxxxxxx>
---
Changes in v4:
- Keep -EINVAL for the VFE core clock, clamp only the other clocks,
  drop the warning (Bryan O'Donoghue, Loic Poulain)
- Dropped Reviewed-by due to changes

 drivers/media/platform/qcom/camss/camss-vfe.c | 40 +++++++++++++++++--
 1 file changed, 36 insertions(+), 4 deletions(-)

diff --git a/drivers/media/platform/qcom/camss/camss-vfe.c b/drivers/media/platform/qcom/camss/camss-vfe.c
index 59be37f83df3..bcc2c1929af1 100644
--- a/drivers/media/platform/qcom/camss/camss-vfe.c
+++ b/drivers/media/platform/qcom/camss/camss-vfe.c
@@ -918,6 +918,20 @@ static int vfe_match_clock_names(struct vfe_device *vfe,
 		!strcmp(clock->name, "camnoc_rt_axi"));
 }
 
+static bool vfe_match_core_clock_name(struct vfe_device *vfe,
+				      struct camss_clock *clock)
+{
+	char vfe_name[7]; /* vfeXXX\0 */
+	char vfe_lite_name[12]; /* vfe_liteXXX\0 */
+
+	snprintf(vfe_name, sizeof(vfe_name), "vfe%d", vfe->id);
+	snprintf(vfe_lite_name, sizeof(vfe_lite_name), "vfe_lite%d", vfe->id);
+
+	return (!strcmp(clock->name, vfe_name) ||
+		!strcmp(clock->name, vfe_lite_name) ||
+		!strcmp(clock->name, "vfe_lite"));
+}
+
 /*
  * vfe_check_clock_levels - Calculate and set clock rates on VFE module
  * @clock: clocks data
@@ -1001,9 +1015,14 @@ static int vfe_set_clock_rates(struct vfe_device *vfe)
 					break;
 
 			if (j == clock->nfreqs) {
-				dev_err(dev,
-					"Pixel clock is too high for VFE");
-				return -EINVAL;
+				if (vfe_match_core_clock_name(vfe, clock)) {
+					dev_err(dev,
+						"Pixel clock is too high for VFE");
+					return -EINVAL;
+				}
+
+				/* Other clocks are clamped to their highest rate */
+				j = clock->nfreqs - 1;
 			}
 
 			/* if sensor pixel clock is not available */
@@ -1045,10 +1064,23 @@ static int vfe_check_clock_rates(struct vfe_device *vfe)
 		struct camss_clock *clock = &vfe->clock[i];
 
 		if (vfe_match_clock_names(vfe, clock) && vfe_check_clock_levels(clock)) {
+			u64 req_rate = min_rate;
 			unsigned long rate;
 
+			if (!vfe_match_core_clock_name(vfe, clock)) {
+				long max_rate;
+
+				/* A clock already at its highest rate cannot go higher */
+				max_rate = clk_round_rate(clock->clk,
+							  clock->freq[clock->nfreqs - 1]);
+				if (max_rate < 0)
+					return max_rate;
+
+				req_rate = min_t(u64, min_rate, max_rate);
+			}
+
 			rate = clk_get_rate(clock->clk);
-			if (rate < min_rate)
+			if (rate < req_rate)
 				return -EBUSY;
 		}
 	}
-- 
2.34.1