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Date: Tue, 28 Jul 2020 09:04:32 -0700
From: Sowjanya Komatineni <skomatineni@...dia.com>
To: Dmitry Osipenko <digetx@...il.com>, <thierry.reding@...il.com>,
<jonathanh@...dia.com>, <frankc@...dia.com>, <hverkuil@...all.nl>,
<sakari.ailus@....fi>, <robh+dt@...nel.org>,
<helen.koike@...labora.com>
CC: <sboyd@...nel.org>, <gregkh@...uxfoundation.org>,
<linux-media@...r.kernel.org>, <devicetree@...r.kernel.org>,
<linux-tegra@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
<linux-i2c@...r.kernel.org>
Subject: Re: [RFC PATCH v5 12/14] gpu: host1x: mipi: Keep MIPI clock enabled
till calibration is done
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@...dia.com>
>> ---
>> 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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