linux-kernel - Re: [PATCH v2] usb: musb: debugfs: allow forcing host mode together with speed in testmode

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Date:   Mon, 19 Dec 2016 09:10:39 -0600
From:   Bin Liu <b-liu@...com>
To:     Pali Rohár <pali.rohar@...il.com>
CC:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        <linux-usb@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        Tony Lindgren <tony@...mide.com>,
        joerg Reisenweber <joerg@...nmoko.org>,
        <linux-omap@...r.kernel.org>,
        Ivaylo Dimitrov <ivo.g.dimitrov.75@...il.com>,
        Sebastian Reichel <sre@...nel.org>,
        Aaro Koskinen <aaro.koskinen@....fi>,
        Pavel Machek <pavel@....cz>, Nishanth Menon <nm@...com>,
        Felipe Balbi <balbi@...nel.org>
Subject: Re: [PATCH v2] usb: musb: debugfs: allow forcing host mode together
 with speed in testmode

On Sun, Dec 18, 2016 at 12:54:40AM +0100, Pali Rohár wrote:
> Based on the musb ug, force_host bit is allowed to be set along with
> force_hs or force_fs bit.
> 
> It could help to implement forced host mode via testmode on Nokia N900.
> 
> Signed-off-by: Pali Rohár <pali.rohar@...il.com>
> ---
> Changes in v2:
> * Use == instead of & for comparison of testmode
> ---
>  drivers/usb/musb/musb_debugfs.c |   44 +++++++++++++++++++++++++--------------
>  1 file changed, 28 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/usb/musb/musb_debugfs.c b/drivers/usb/musb/musb_debugfs.c
> index 9b22d94..5308cea 100644
> --- a/drivers/usb/musb/musb_debugfs.c
> +++ b/drivers/usb/musb/musb_debugfs.c
> @@ -147,28 +147,34 @@ static int musb_test_mode_show(struct seq_file *s, void *unused)
>  
>  	test = musb_readb(musb->mregs, MUSB_TESTMODE);
>  
> -	if (test & MUSB_TEST_FORCE_HOST)
> +	if (test == (MUSB_TEST_FORCE_HOST | MUSB_TEST_FORCE_FS))
> +		seq_printf(s, "force host full-speed\n");
> +
> +	else if (test == (MUSB_TEST_FORCE_HOST | MUSB_TEST_FORCE_HS))
> +		seq_printf(s, "force host high-speed\n");
> +
> +	else if (test == MUSB_TEST_FORCE_HOST)
>  		seq_printf(s, "force host\n");
>  
> -	if (test & MUSB_TEST_FIFO_ACCESS)
> +	else if (test == MUSB_TEST_FIFO_ACCESS)
>  		seq_printf(s, "fifo access\n");
>  
> -	if (test & MUSB_TEST_FORCE_FS)
> +	else if (test == MUSB_TEST_FORCE_FS)
>  		seq_printf(s, "force full-speed\n");
>  
> -	if (test & MUSB_TEST_FORCE_HS)
> +	else if (test == MUSB_TEST_FORCE_HS)
>  		seq_printf(s, "force high-speed\n");
>  
> -	if (test & MUSB_TEST_PACKET)
> +	else if (test == MUSB_TEST_PACKET)
>  		seq_printf(s, "test packet\n");
>  
> -	if (test & MUSB_TEST_K)
> +	else if (test == MUSB_TEST_K)
>  		seq_printf(s, "test K\n");
>  
> -	if (test & MUSB_TEST_J)
> +	else if (test == MUSB_TEST_J)
>  		seq_printf(s, "test J\n");
>  
> -	if (test & MUSB_TEST_SE0_NAK)
> +	else if (test == MUSB_TEST_SE0_NAK)
>  		seq_printf(s, "test SE0 NAK\n");
>  
>  	return 0;
> @@ -206,30 +212,36 @@ static ssize_t musb_test_mode_write(struct file *file,
>  	if (copy_from_user(buf, ubuf, min_t(size_t, sizeof(buf) - 1, count)))
>  		return -EFAULT;
>  
> -	if (strstarts(buf, "force host"))
> +	if (strstarts(buf, "force host full-speed"))

buf is only 18 bytes long, the string is not fully compared.
You might have to increase buf[] to 24 bytes.

Regards,
-Bin.