Re: [RFC PATCH v3 16/18] gpu: host1x: mipi: Split tegra_mipi_calibrate and tegra_mipi_wait

[Dmitry Osipenko]

17.07.2020 00:09, Sowjanya Komatineni ÐÐÑÐÑ:
> 
> On 7/16/20 1:38 PM, Dmitry Osipenko wrote:
>> 15.07.2020 07:20, Sowjanya Komatineni ÐÐÑÐÑ:
>>> SW can trigger MIPI pads calibration any time after power on
>>> but calibration results will be latched and applied to the pads
>>> by MIPI CAL unit only when the link is in LP-11 state and then
>>> status register will be updated.
>>>
>>> For CSI, trigger of pads calibration happen during CSI stream
>>> enable where CSI receiver is kept ready prior to sensor or CSI
>>> transmitter stream start.
>>>
>>> So, pads may not be in LP-11 at this time and waiting for the
>>> calibration to be done immediate after calibration start will
>>> result in timeout.
>>>
>>> This patch splits tegra_mipi_calibrate() and tegra_mipi_wait()
>>> so triggering for calibration and waiting for it to complete can
>>> happen at different stages.
>>>
>>> Signed-off-by: Sowjanya Komatineni <skomatineni@xxxxxxxxxx>
>>> ---
>> ...
>>> Â int tegra_mipi_calibrate(struct tegra_mipi_device *device)
>>> Â {
>>> @@ -370,12 +381,10 @@ int tegra_mipi_calibrate(struct
>>> tegra_mipi_device *device)
>>> ÂÂÂÂÂ value |= MIPI_CAL_CTRL_START;
>>> ÂÂÂÂÂ tegra_mipi_writel(device->mipi, value, MIPI_CAL_CTRL);
>>> Â -ÂÂÂ err = tegra_mipi_wait(device->mipi);
>> Doesn't MIPI clock need to be enabled during of the calibration process?
> MIPI clock is already enabled in tegra_mipi_calibrate
>>
>>> ÂÂÂÂÂ mutex_unlock(&device->mipi->lock);
>>> ÂÂÂÂÂ clk_disable(device->mipi->clk);

What keeps MIPI clock enabled after completion of the
tegra_mipi_calibrate() invocation?

>>> Â -ÂÂÂ return err;
>>> +ÂÂÂ return 0;
>>> Â }
>>> Â EXPORT_SYMBOL(tegra_mipi_calibrate);