linux-kernel - Re: [PATCH v5 2/2] phy: rockchip-inno-usb2: add a new driver for Rockchip usb2phy

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Message-ID: <da45cb15-4823-0992-0b83-475f1ad4c8aa@rock-chips.com>
Date:	Wed, 15 Jun 2016 18:58:43 +0800
From:	Frank Wang <frank.wang@...k-chips.com>
To:	Heiko Stübner <heiko@...ech.de>
Cc:	dianders@...omium.org, linux@...ck-us.net, groeck@...omium.org,
	jwerner@...omium.org, kishon@...com, robh+dt@...nel.org,
	pawel.moll@....com, mark.rutland@....com,
	ijc+devicetree@...lion.org.uk, galak@...eaurora.org,
	linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
	linux-usb@...r.kernel.org, linux-rockchip@...ts.infradead.org,
	xzy.xu@...k-chips.com, kever.yang@...k-chips.com,
	huangtao@...k-chips.com, william.wu@...k-chips.com,
	frank.wang@...k-chips.com
Subject: Re: [PATCH v5 2/2] phy: rockchip-inno-usb2: add a new driver for
 Rockchip usb2phy

Hi Heiko,

On 2016/6/15 17:04, Heiko Stübner wrote:
> Hi Frank,
>
> Am Mittwoch, 15. Juni 2016, 11:23:26 schrieb Frank Wang:
>> On 2016/6/14 21:27, Heiko Stübner wrote:
>>> Am Montag, 13. Juni 2016, 10:10:10 schrieb Frank Wang:
>>>> The newer SoCs (rk3366, rk3399) take a different usb-phy IP block
>>>> than rk3288 and before, and most of phy-related registers are also
>>>> different from the past, so a new phy driver is required necessarily.
>>>>
>>>> Signed-off-by: Frank Wang <frank.wang@...k-chips.com>
>>>> ---
>>>>
>>>> Changes in v5:
>>>>    - Added 'reg' in the data block to match the different phy-blocks in
>>>>    dt.
>>>>
>>>> Changes in v4:
>>>>    - Removed some processes related to 'vbus_host-supply'.
>>>>
>>>> Changes in v3:
>>>>    - Resolved the mapping defect between fixed value in driver and the
>>>>
>>>> property in devicetree.
>>>>
>>>>    - Optimized 480m output clock register function.
>>>>    - Code cleanup.
>>>>
>>>> Changes in v2:
>>>>    - Changed vbus_host operation from gpio to regulator in *_probe.
>>>>    - Improved the fault treatment relate to 480m clock register.
>>>>    - Cleaned up some meaningless codes in *_clk480m_disable.
>>>>    - made more clear the comment of *_sm_work.
>>>>    
>>>>    drivers/phy/Kconfig                  |    7 +
>>>>    drivers/phy/Makefile                 |    1 +
>>>>    drivers/phy/phy-rockchip-inno-usb2.c |  645
>>>>
>>>> ++++++++++++++++++++++++++++++++++ 3 files changed, 653 insertions(+)
>>>>
>>>> [...]
>>>>
>>>> +
>>>> +static int rockchip_usb2phy_exit(struct phy *phy)
>>>> +{
>>>> +	struct rockchip_usb2phy_port *rport = phy_get_drvdata(phy);
>>>> +
>>>>
>>> 	if (!rport->port_cfg)
>>> 	
>>> 		return 0;
>>>> +	if (rport->port_id == USB2PHY_PORT_HOST)
>>>> +		cancel_delayed_work_sync(&rport->sm_work);
>>>> +
>>> you will also need to resume the port here, if it is suspended at this
>>> point, as phy_power_off gets called after phy_exit and would probably
>>> produce clk enable/disable mismatches otherwise.
>> Hmm, from my personal point of view, when canceling sm_work here, it may
>> not cause the port goes to suspend, isn't it? besides, clk only prepared
>> in *_usb2phy_resume(), and unprepared in *_usb2phy_suspend(), so if we
>> resume port here,  the prepare_count of clk will be increased again, I
>> am afraid this is not correct, and am I wrong? would you like to tell me
>> more details?
> usb2phy_resume gets called both initially through phy_power_on as well.
> So it's on but through the first scheduled work call, might get suspended when
> nothing is connected. (clk_enable and clk_disable will run).
> If nothing is connected on unload phy_power_off will get called while the
> clock actually is still disabled.
>
> So I think it's either resuming on exit, or at least making sure to do nothing
> in that case in the phy_power_off callback of the driver.
>
>

Well, I got what you mean. I saw phy_power_on() gets called  twice at 
ehci/ohci driver probe time, one is at pdata->power_on(); another is at 
usb_add_hcd(), so after that, the power_count of phy increases to two. 
however, when ehci/ohci driver goes to suspend, there is only once to 
call phy_power_off(), and the power_count of phy decreases to 1, so our 
usb2phy_resume() could not be invoked :-) .

If so, is it still need to care it? How about use suspended member of 
rockchip_usb2phy_port as a conditional to check in *_usb2phy_suspend(), 
if necessary.

BR.
Frank