Re: [RFC PATCH v5 12/14] gpu: host1x: mipi: Keep MIPI clock enabled till calibration is done

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On 7/28/20 4:03 AM, Dmitry Osipenko wrote:
27.07.2020 23:57, Sowjanya Komatineni пишет:
With the split of MIPI calibration into tegra_mipi_calibrate() and
tegra_mipi_wait(), MIPI clock is not kept enabled till the calibration
is done.

So, this patch skips disabling MIPI clock after triggering start of
calibration and disables it only after waiting for done status from
the calibration logic.

This patch renames tegra_mipi_calibrate() as tegra_mipi_start_calibration()
and tegra_mipi_wait() as tegra_mipi_finish_calibration() to be inline
with their usage.

As MIPI clock is left enabled and in case of any failures with CSI input
streaming tegra_mipi_finish_calibration() will not get invoked.
So added new API tegra_mipi_cancel_calibration() which disables MIPI clock
and consumer drivers can call this in such cases.

Signed-off-by: Sowjanya Komatineni <skomatineni@xxxxxxxxxx>
---
  drivers/gpu/drm/tegra/dsi.c |  4 ++--
  drivers/gpu/host1x/mipi.c   | 19 ++++++++++---------
  include/linux/host1x.h      |  5 +++--
  3 files changed, 15 insertions(+), 13 deletions(-)

diff --git a/drivers/gpu/drm/tegra/dsi.c b/drivers/gpu/drm/tegra/dsi.c
index 3820e8d..a7864e9 100644
--- a/drivers/gpu/drm/tegra/dsi.c
+++ b/drivers/gpu/drm/tegra/dsi.c
@@ -694,11 +694,11 @@ static int tegra_dsi_pad_calibrate(struct tegra_dsi *dsi)
  		DSI_PAD_PREEMP_PD(0x03) | DSI_PAD_PREEMP_PU(0x3);
  	tegra_dsi_writel(dsi, value, DSI_PAD_CONTROL_3);
- err = tegra_mipi_calibrate(dsi->mipi);
+	err = tegra_mipi_start_calibration(dsi->mipi);
  	if (err < 0)
  		return err;
- return tegra_mipi_wait(dsi->mipi);
+	return tegra_mipi_finish_calibration(dsi->mipi);
  }
static void tegra_dsi_set_timeout(struct tegra_dsi *dsi, unsigned long bclk,
diff --git a/drivers/gpu/host1x/mipi.c b/drivers/gpu/host1x/mipi.c
index e606464..b15ab6e 100644
--- a/drivers/gpu/host1x/mipi.c
+++ b/drivers/gpu/host1x/mipi.c
@@ -293,17 +293,19 @@ int tegra_mipi_disable(struct tegra_mipi_device *dev)
  }
  EXPORT_SYMBOL(tegra_mipi_disable);
-int tegra_mipi_wait(struct tegra_mipi_device *device)
+void tegra_mipi_cancel_calibration(struct tegra_mipi_device *device)
+{
Doesn't MIPI_CAL need to be reset here?
No need to reset MIPI CAL

+	clk_disable(device->mipi->clk);
+}
+EXPORT_SYMBOL(tegra_mipi_cancel_calibration);
+
+int tegra_mipi_finish_calibration(struct tegra_mipi_device *device)
  {
  	struct tegra_mipi *mipi = device->mipi;
  	void __iomem *status_reg = mipi->regs + (MIPI_CAL_STATUS << 2);
  	u32 value;
  	int err;
- err = clk_enable(device->mipi->clk);
-	if (err < 0)
-		return err;
-
  	mutex_lock(&device->mipi->lock);
err = readl_relaxed_poll_timeout(status_reg, value,
@@ -315,9 +317,9 @@ int tegra_mipi_wait(struct tegra_mipi_device *device)
return err;
  }
-EXPORT_SYMBOL(tegra_mipi_wait);
+EXPORT_SYMBOL(tegra_mipi_finish_calibration);
-int tegra_mipi_calibrate(struct tegra_mipi_device *device)
+int tegra_mipi_start_calibration(struct tegra_mipi_device *device)
  {
  	const struct tegra_mipi_soc *soc = device->mipi->soc;
  	unsigned int i;
@@ -382,11 +384,10 @@ int tegra_mipi_calibrate(struct tegra_mipi_device *device)
  	tegra_mipi_writel(device->mipi, value, MIPI_CAL_CTRL);
This function sets MIPI_CAL_CLKEN_OVR bit, does it mean that MIPI clock
becomes always-ON?

I don't see where MIPI_CAL_CLKEN_OVR is unset.

CLKEN_OVR was always kept enabled in the driver prior to my patch and I was not touching that.

But as we are turning ON/OFF MIPI clock itself no need to unset CLKEN_OVR


  	mutex_unlock(&device->mipi->lock);
-	clk_disable(device->mipi->clk);
return 0;
  }
-EXPORT_SYMBOL(tegra_mipi_calibrate);
+EXPORT_SYMBOL(tegra_mipi_start_calibration);
static const struct tegra_mipi_pad tegra114_mipi_pads[] = {
  	{ .data = MIPI_CAL_CONFIG_CSIA },
diff --git a/include/linux/host1x.h b/include/linux/host1x.h
index 20c885d..b490dda 100644
--- a/include/linux/host1x.h
+++ b/include/linux/host1x.h
@@ -333,7 +333,8 @@ struct tegra_mipi_device *tegra_mipi_request(struct device *device,
  void tegra_mipi_free(struct tegra_mipi_device *device);
  int tegra_mipi_enable(struct tegra_mipi_device *device);
  int tegra_mipi_disable(struct tegra_mipi_device *device);
-int tegra_mipi_calibrate(struct tegra_mipi_device *device);
-int tegra_mipi_wait(struct tegra_mipi_device *device);
+int tegra_mipi_start_calibration(struct tegra_mipi_device *device);
+int tegra_mipi_finish_calibration(struct tegra_mipi_device *device);
+void tegra_mipi_cancel_calibration(struct tegra_mipi_device *device);
#endif





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