linux-kernel - Re: [PATCH] usb: dwc2: gadget: fix dwc2_check_param_tx_fifo

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Date:   Thu, 30 Nov 2017 09:43:01 +0000
From:   Minas Harutyunyan <Minas.Harutyunyan@...opsys.com>
To:     Amelie Delaunay <amelie.delaunay@...com>,
        John Youn <John.Youn@...opsys.com>,
        Felipe Balbi <balbi@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
CC:     "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] usb: dwc2: gadget: fix dwc2_check_param_tx_fifo_sizes

Hi Amelie,

On 11/27/2017 6:42 PM, Amelie Delaunay wrote:
> In case of OTG mode, with an OTG adapter plugged, the
> dwc2_check_param_tx_fifo_sizes function reads DPTXFSIZN registers while
> the controller is in Host mode, and, because DPTXFSIZN registers are
> Device specific registers, the values read are 0.
> Then, g_tx_fifo_size[fifo] values are considered invalid because in the
> comparison test, they need to be greater than min and lower than dptxfszn
> which is 0.
> To fix this issue, force the controller in device mode if needed before
> reading the DPTXFSIZN registers, and restore the previous mode if needed
> after reading.
> 
> Fixes: 3c6aea7344c3 ("usb: dwc2: gadget: Add checking for g-tx-fifo-size
> parameter")
> Signed-off-by: Amelie Delaunay <amelie.delaunay@...com>
> ---
>   drivers/usb/dwc2/params.c | 10 ++++++++++
>   1 file changed, 10 insertions(+)
> 
> diff --git a/drivers/usb/dwc2/params.c b/drivers/usb/dwc2/params.c
> index ef73af6..302fefb 100644
> --- a/drivers/usb/dwc2/params.c
> +++ b/drivers/usb/dwc2/params.c
> @@ -469,6 +469,7 @@ static void dwc2_check_param_tx_fifo_sizes(struct dwc2_hsotg *hsotg)
>   	int fifo;
>   	int min;
>   	u32 total = 0;
> +	bool forced;
>   	u32 dptxfszn;
>   
>   	fifo_count = dwc2_hsotg_tx_fifo_count(hsotg);
> @@ -483,6 +484,12 @@ static void dwc2_check_param_tx_fifo_sizes(struct dwc2_hsotg *hsotg)
>   		dwc2_set_param_tx_fifo_sizes(hsotg);
>   	}
>   
> +	/*
> +	 * Reading DPTXFSIZN registers requires the controller to be in device
> +	 * mode. The mode will be forced, if necessary, to read these values.
> +	 */
> +	forced = dwc2_force_mode_if_needed(hsotg, false);
> +
>   	for (fifo = 1; fifo <= fifo_count; fifo++) {
>   		dptxfszn = (dwc2_readl(hsotg->regs + DPTXFSIZN(fifo)) &
>   			FIFOSIZE_DEPTH_MASK) >> FIFOSIZE_DEPTH_SHIFT;
> @@ -495,6 +502,9 @@ static void dwc2_check_param_tx_fifo_sizes(struct dwc2_hsotg *hsotg)
>   			hsotg->params.g_tx_fifo_size[fifo] = dptxfszn;
>   		}
>   	}
> +
> +	if (forced)
> +		dwc2_clear_force_mode(hsotg);
>   }
>   
>   #define CHECK_RANGE(_param, _min, _max, _def) do {			\
> 

I'll recommend to use "[PATCH] usb: dwc2: Fix TxFIFOn sizes and total 
TxFIFO size issues" instead.

Thanks,
Minas