diff mbox series

[v6,06/12] media: ov5640: Compute the clock rate at runtime

Message ID 284e2b654a03e0817b6af8b68f18cbc183024a62.1543826654.git-series.maxime.ripard@bootlin.com (mailing list archive)
State New, archived
Headers show
Series media: ov5640: Misc cleanup and improvements | expand

Commit Message

Maxime Ripard Dec. 3, 2018, 8:44 a.m. UTC 
The clock rate, while hardcoded until now, is actually a function of the
resolution, framerate and bytes per pixel. Now that we have an algorithm to
adjust our clock rate, we can select it dynamically when we change the
mode.

This changes a bit the clock rate being used, with the following effect:

+------+------+------+------+-----+-----------------+----------------+-----------+
| Hact | Vact | Htot | Vtot | FPS | Hardcoded clock | Computed clock | Deviation |
+------+------+------+------+-----+-----------------+----------------+-----------+
|  640 |  480 | 1896 | 1080 |  15 |        56000000 |       61430400 | 8.84 %    |
|  640 |  480 | 1896 | 1080 |  30 |       112000000 |      122860800 | 8.84 %    |
| 1024 |  768 | 1896 | 1080 |  15 |        56000000 |       61430400 | 8.84 %    |
| 1024 |  768 | 1896 | 1080 |  30 |       112000000 |      122860800 | 8.84 %    |
|  320 |  240 | 1896 |  984 |  15 |        56000000 |       55969920 | 0.05 %    |
|  320 |  240 | 1896 |  984 |  30 |       112000000 |      111939840 | 0.05 %    |
|  176 |  144 | 1896 |  984 |  15 |        56000000 |       55969920 | 0.05 %    |
|  176 |  144 | 1896 |  984 |  30 |       112000000 |      111939840 | 0.05 %    |
|  720 |  480 | 1896 |  984 |  15 |        56000000 |       55969920 | 0.05 %    |
|  720 |  480 | 1896 |  984 |  30 |       112000000 |      111939840 | 0.05 %    |
|  720 |  576 | 1896 |  984 |  15 |        56000000 |       55969920 | 0.05 %    |
|  720 |  576 | 1896 |  984 |  30 |       112000000 |      111939840 | 0.05 %    |
| 1280 |  720 | 1892 |  740 |  15 |        42000000 |       42002400 | 0.01 %    |
| 1280 |  720 | 1892 |  740 |  30 |        84000000 |       84004800 | 0.01 %    |
| 1920 | 1080 | 2500 | 1120 |  15 |        84000000 |       84000000 | 0.00 %    |
| 1920 | 1080 | 2500 | 1120 |  30 |       168000000 |      168000000 | 0.00 %    |
| 2592 | 1944 | 2844 | 1944 |  15 |        84000000 |      165862080 | 49.36 %   |
+------+------+------+------+-----+-----------------+----------------+-----------+

Only the 640x480, 1024x768 and 2592x1944 modes are significantly affected
by the new formula.

In this case, 640x480 and 1024x768 are actually fixed by this change.
Indeed, the sensor was sending data at, for example, 27.33fps instead of
30fps. This is -9%, which is roughly what we're seeing in the array.
Testing these modes with the new clock setup actually fix that error, and
data are now sent at around 30fps.

2592x1944, on the other hand, is probably due to the fact that this mode
can only be used using MIPI-CSI2, in a two lane mode, and never really
tested with a DVP bus.

Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
Tested-by: Adam Ford <aford173@gmail.com> #imx6dq
---
 drivers/media/i2c/ov5640.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/drivers/media/i2c/ov5640.c b/drivers/media/i2c/ov5640.c
index e36b04912dcc..536261618d0d 100644
--- a/drivers/media/i2c/ov5640.c
+++ b/drivers/media/i2c/ov5640.c
@@ -1992,7 +1992,8 @@  static int ov5640_set_mode(struct ov5640_dev *sensor)
 	 * All the formats we support have 16 bits per pixel, seems to require
 	 * the same rate than YUV, so we can just use 16 bpp all the time.
 	 */
-	rate = mode->pixel_clock * 16;
+	rate = mode->vtot * mode->htot * 16;
+	rate *= ov5640_framerates[sensor->current_fr];
 	if (sensor->ep.bus_type == V4L2_MBUS_CSI2_DPHY) {
 		rate = rate / sensor->ep.bus.mipi_csi2.num_data_lanes;
 		ret = ov5640_set_mipi_pclk(sensor, rate);