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

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Date:	Wed, 15 Jun 2016 20:49:30 +0200
From:	Heiko Stübner <heiko@...ech.de>
To:	Frank Wang <frank.wang@...k-chips.com>
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
Subject: Re: [PATCH v5 2/2] phy: rockchip-inno-usb2: add a new driver for Rockchip usb2phy

Hi Frank,

Am Mittwoch, 15. Juni 2016, 18:58:43 schrieb Frank Wang:
> On 2016/6/15 17:04, Heiko Stübner wrote:
> > 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?

You should never have to rely on oddities in other drivers :-)

> How about use suspended member of
> rockchip_usb2phy_port as a conditional to check in *_usb2phy_suspend(),
> if necessary.

That looks also sane and should work.


Heiko