From: Martin Tůma <martin.tuma@xxxxxxxxxxxxxxxxxxxxx>
Properly document the function of the mgb4 output frame_rate sysfs parameter
and fix the corner case when the frame rate is set to zero causing a "divide
by zero" kernel panic.
Signed-off-by: Martin Tůma <martin.tuma@xxxxxxxxxxxxxxxxxxxxx>
---
Documentation/admin-guide/media/mgb4.rst | 8 ++++++--
drivers/media/pci/mgb4/mgb4_sysfs_out.c | 9 +++++----
drivers/media/pci/mgb4/mgb4_vout.c | 12 ++++++------
drivers/media/pci/mgb4/mgb4_vout.h | 2 +-
4 files changed, 18 insertions(+), 13 deletions(-)
diff --git a/Documentation/admin-guide/media/mgb4.rst b/Documentation/admin-guide/media/mgb4.rst
index 2977f74d7e26..6fff886003e2 100644
--- a/Documentation/admin-guide/media/mgb4.rst
+++ b/Documentation/admin-guide/media/mgb4.rst
@@ -228,8 +228,12 @@ Common FPDL3/GMSL output parameters
open.*
**frame_rate** (RW):
- Output video frame rate in frames per second. The default frame rate is
- 60Hz.
+ Output video signal frame rate limit in frames per second. Due to
+ the limited output pixel clock steps, the card can not always generate
+ a frame rate perfectly matching the value required by the connected display.
+ Using this parameter one can limit the frame rate by "crippling" the signal
+ so that the lines are not equal but the signal appears like having the exact
+ frame rate to the connected display. The default frame rate limit is 60Hz.
**hsync_polarity** (RW):
HSYNC signal polarity.
diff --git a/drivers/media/pci/mgb4/mgb4_sysfs_out.c b/drivers/media/pci/mgb4/mgb4_sysfs_out.c
index f67ff2a48329..573aa61c69d4 100644
--- a/drivers/media/pci/mgb4/mgb4_sysfs_out.c
+++ b/drivers/media/pci/mgb4/mgb4_sysfs_out.c
@@ -229,9 +229,9 @@ static ssize_t frame_rate_show(struct device *dev,
struct video_device *vdev = to_video_device(dev);
struct mgb4_vout_dev *voutdev = video_get_drvdata(vdev);
u32 period = mgb4_read_reg(&voutdev->mgbdev->video,
- voutdev->config->regs.frame_period);
+ voutdev->config->regs.frame_limit);
- return sprintf(buf, "%u\n", MGB4_HW_FREQ / period);
+ return sprintf(buf, "%u\n", period ? MGB4_HW_FREQ / period : 0);
}
/*
@@ -245,14 +245,15 @@ static ssize_t frame_rate_store(struct device *dev,
struct video_device *vdev = to_video_device(dev);
struct mgb4_vout_dev *voutdev = video_get_drvdata(vdev);
unsigned long val;
- int ret;
+ int limit, ret;
ret = kstrtoul(buf, 10, &val);
if (ret)
return ret;
+ limit = val ? MGB4_HW_FREQ / val : 0;
mgb4_write_reg(&voutdev->mgbdev->video,
- voutdev->config->regs.frame_period, MGB4_HW_FREQ / val);
+ voutdev->config->regs.frame_limit, limit);
return count;
}
diff --git a/drivers/media/pci/mgb4/mgb4_vout.c b/drivers/media/pci/mgb4/mgb4_vout.c
index a6b55669f0a8..cd001ceaae63 100644
--- a/drivers/media/pci/mgb4/mgb4_vout.c
+++ b/drivers/media/pci/mgb4/mgb4_vout.c
@@ -680,12 +680,12 @@ static void fpga_init(struct mgb4_vout_dev *voutdev)
mgb4_write_reg(video, regs->config, 0x00000011);
mgb4_write_reg(video, regs->resolution,
(DEFAULT_WIDTH << 16) | DEFAULT_HEIGHT);
- mgb4_write_reg(video, regs->hsync, 0x00102020);
- mgb4_write_reg(video, regs->vsync, 0x40020202);
- mgb4_write_reg(video, regs->frame_period, DEFAULT_PERIOD);
+ mgb4_write_reg(video, regs->hsync, 0x00283232);
+ mgb4_write_reg(video, regs->vsync, 0x40141F1E);
+ mgb4_write_reg(video, regs->frame_limit, DEFAULT_PERIOD);
mgb4_write_reg(video, regs->padding, 0x00000000);
- voutdev->freq = mgb4_cmt_set_vout_freq(voutdev, 70000 >> 1) << 1;
+ voutdev->freq = mgb4_cmt_set_vout_freq(voutdev, 61150 >> 1) << 1;
mgb4_write_reg(video, regs->config,
(voutdev->config->id + MGB4_VIN_DEVICES) << 2 | 1 << 4);
@@ -711,8 +711,8 @@ static void debugfs_init(struct mgb4_vout_dev *voutdev)
voutdev->regs[3].offset = voutdev->config->regs.hsync;
voutdev->regs[4].name = "VIDEO_PARAMS_2";
voutdev->regs[4].offset = voutdev->config->regs.vsync;
- voutdev->regs[5].name = "FRAME_PERIOD";
- voutdev->regs[5].offset = voutdev->config->regs.frame_period;
+ voutdev->regs[5].name = "FRAME_LIMIT";
+ voutdev->regs[5].offset = voutdev->config->regs.frame_limit;
voutdev->regs[6].name = "PADDING_PIXELS";
voutdev->regs[6].offset = voutdev->config->regs.padding;
if (has_timeperframe(video)) {
diff --git a/drivers/media/pci/mgb4/mgb4_vout.h b/drivers/media/pci/mgb4/mgb4_vout.h
index ab9b58b1deb7..adc8fe1e7ae6 100644
--- a/drivers/media/pci/mgb4/mgb4_vout.h
+++ b/drivers/media/pci/mgb4/mgb4_vout.h
@@ -19,7 +19,7 @@ struct mgb4_vout_regs {
u32 config;
u32 status;
u32 resolution;
- u32 frame_period;
+ u32 frame_limit;
u32 hsync;
u32 vsync;
u32 padding;
--
2.44.0
