linux-kernel - Re: [PATCH 2/4] usb: dwc3: Fix gadget pullup in SS mode

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Message-ID: <20120919115306.GG3772@arwen.pp.htv.fi>
Date:	Wed, 19 Sep 2012 14:53:10 +0300
From:	Felipe Balbi <balbi@...com>
To:	Kishon Vijay Abraham I <kishon@...com>
Cc:	grant.likely@...retlab.ca, rob.herring@...xeda.com,
	rob@...dley.net, linux@....linux.org.uk, balbi@...com,
	linux-usb@...r.kernel.org, linux-omap@...r.kernel.org,
	devicetree-discuss@...ts.ozlabs.org, linux-doc@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	Moiz Sonasath <m-sonasath@...com>
Subject: Re: [PATCH 2/4] usb: dwc3: Fix gadget pullup in SS mode

Hi,

On Wed, Sep 19, 2012 at 05:00:27PM +0530, Kishon Vijay Abraham I wrote:
> From: Moiz Sonasath <m-sonasath@...com>
> 
> For the gadget pullup functionality to work in
> SS mode it requires a particular sequence of
> toggling the run-stop bit. Here is the required
> sequence:
> 
> - Set DCTL[31]
> - Clear DCTL[31]
> - Clear OMAP5430_CONTROL_CORE__PHY_POWER_USB[14]
> - Clear DCTL[8:5] = 0x00
> - Set DCTL[8:5] = 0x05
> - Wait 25 Ms
> - Set DCTL[31]
> - Set OMAP5430_CONTROL_CORE__PHY_POWER_USB[14]
> 
> Tested rigourously the gadget pull-up functionality
> in bot HS and SS modes.
> 
> Signed-off-by: Moiz Sonasath <m-sonasath@...com>
> Signed-off-by: Kishon Vijay Abraham I <kishon@...com>

this needs to split into three patches:

add new poweron field, implement it on omap-usb3, use it on
dwc3/gadget.c

btw, I don't think the changes to run_stop bit are necessary and if they
are, that'd either be a silicon errata or it would've been mentioned on
the databook. I don't remember seeing that on the databook so I'm
assuming that this is caused by a bad use of the PHY.

Why that mdelay(25) ? why 25 ms ? That's quite a long time, actually.

> ---
>  drivers/usb/dwc3/gadget.c   |   21 +++++++++++++++------
>  drivers/usb/phy/omap-usb3.c |   16 ++++++++++++++++
>  include/linux/usb/phy.h     |   10 +++++++++-
>  3 files changed, 40 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
> index 58fdfad..bcc0102 100644
> --- a/drivers/usb/dwc3/gadget.c
> +++ b/drivers/usb/dwc3/gadget.c
> @@ -49,6 +49,7 @@
>  
>  #include <linux/usb/ch9.h>
>  #include <linux/usb/gadget.h>
> +#include <linux/usb/otg.h>
>  
>  #include "core.h"
>  #include "gadget.h"
> @@ -1417,19 +1418,27 @@ static int dwc3_gadget_run_stop(struct dwc3 *dwc, int is_on)
>  	reg = dwc3_readl(dwc->regs, DWC3_DCTL);
>  	if (is_on) {
>  		if (dwc->revision <= DWC3_REVISION_187A) {
> -			reg &= ~DWC3_DCTL_TRGTULST_MASK;
> -			reg |= DWC3_DCTL_TRGTULST_RX_DET;
> +			reg &= ~DWC3_DCTL_ULSTCHNGREQ_MASK;
> +			dwc3_writel(dwc->regs, DWC3_DCTL, reg);
> +			reg |= DWC3_DCTL_ULSTCHNG_RX_DETECT;
> +			dwc3_writel(dwc->regs, DWC3_DCTL, reg);
> +			mdelay(25);
> +			reg |= DWC3_DCTL_RUN_STOP;
> +			dwc3_writel(dwc->regs, DWC3_DCTL, reg);
> +			usb_phy_poweron(dwc->usb3_phy);
>  		}
>  
> -		if (dwc->revision >= DWC3_REVISION_194A)
> +		if (dwc->revision >= DWC3_REVISION_194A) {
>  			reg &= ~DWC3_DCTL_KEEP_CONNECT;
> -		reg |= DWC3_DCTL_RUN_STOP;
> +			reg |= DWC3_DCTL_RUN_STOP;
> +			dwc3_writel(dwc->regs, DWC3_DCTL, reg);
> +		}
>  	} else {
>  		reg &= ~DWC3_DCTL_RUN_STOP;
> +		dwc3_writel(dwc->regs, DWC3_DCTL, reg);
> +		usb_phy_shutdown(dwc->usb3_phy);
>  	}
>  
> -	dwc3_writel(dwc->regs, DWC3_DCTL, reg);

I'd prefer to hold all values on the variable and write only one.

-- 
balbi

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