Re: [PATCH V2] clk: vc5: Add suspend/resume support

[Marek Vasut <marek.vasut@gmail.com>]

On 12/12/2018 09:43 AM, Laurent Pinchart wrote:
> Hi Marex,

Hi,

> Thank you for the patch.
> 
> On Wednesday, 12 December 2018 03:41:30 EET Marek Vasut wrote:
>> Add simple suspend/resume handlers to the driver to restore the chip
>> configuration after resume. It is possible that the chip was configured
>> with non-default values before suspend-resume cycle and that the chip
>> is powered down during this cycle, so the configuration could get lost.
>>
>> Signed-off-by: Marek Vasut <marek.vasut+renesas@gmail.com>
>> Cc: Alexey Firago <alexey_firago@mentor.com>
>> Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
>> Cc: Michael Turquette <mturquette@baylibre.com>
>> Cc: Stephen Boyd <sboyd@codeaurora.org>
>> Cc: linux-renesas-soc@vger.kernel.org
>> ---
>> V2: Replace ifdef with __maybe_unused
>>     Simplify return value handling in resume
>> ---
>>  drivers/clk/clk-versaclock5.c | 31 +++++++++++++++++++++++++++++++
>>  1 file changed, 31 insertions(+)
>>
>> diff --git a/drivers/clk/clk-versaclock5.c b/drivers/clk/clk-versaclock5.c
>> index decffb3826ec..b66586a3abb7 100644
>> --- a/drivers/clk/clk-versaclock5.c
>> +++ b/drivers/clk/clk-versaclock5.c
>> @@ -906,6 +906,34 @@ static int vc5_remove(struct i2c_client *client)
>>  	return 0;
>>  }
>>
>> +static int __maybe_unused vc5_suspend(struct device *dev)
>> +{
>> +	struct vc5_driver_data *vc5 = dev_get_drvdata(dev);
>> +	int ret;
>> +
>> +	ret = regcache_sync(vc5->regmap);
> 
> Didn't you say the sync here was unneeded and would be dropped ?
> 
>> +	if (ret != 0) {
>> +		dev_err(dev, "Failed to save register map: %d\n", ret);
>> +		return ret;
>> +	}

If you have a setup with working DU and VGA on something close to next
(it's broken in next), can you try dropping this hunk (basically do
ret = 0;//regcache_sync(vc5->regmap); ) and see if the regcache stays
consistent ? It should. If so, I'll drop this in V3.

>> +	regcache_cache_only(vc5->regmap, true);
>> +	regcache_mark_dirty(vc5->regmap);
[...]


-- 
Best regards,
Marek Vasut