[U-Boot] [PATCH 05/10] dfu: Only perform DFU board_usb_init() for TRATS

From: Lukasz Majewski <l.majewski@majess.pl>
To: u-boot@lists.denx.de
Subject: [U-Boot] [PATCH 05/10] dfu: Only perform DFU board_usb_init() for TRATS
Date: Fri, 30 Nov 2012 00:14:02 +0100	[thread overview]
Message-ID: <20121130001402.3ffc49a3@jawa> (raw)
In-Reply-To: <50B79E96.7010605@ti.com>

Hi Tom,

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> On 11/28/12 11:08, Lukasz Majewski wrote:
> > Hi Tom,
> > 
> > On 11/28/12 09:47, Lukasz Majewski wrote:
> >>>> Hi Pantelis,
> >>>> 
> >>>>> USB initialization shouldn't happen for all the boards.
> >>>>> 
> >>>> 
> >>>> The board_usb_init() follows u-boot policy, that SoC IPs
> >>>> (USB) are enabled and configured just before their usage.
> >>>> 
> >>>> 
> >>>>> Signed-off-by: Pantelis Antoniou
> >>>>> <panto@antoniou-consulting.com> --- common/cmd_dfu.c | 3
> >>>>> +++ 1 file changed, 3 insertions(+)
> >>>>> 
> >>>>> diff --git a/common/cmd_dfu.c b/common/cmd_dfu.c index 
> >>>>> 01d6b3a..327c738 100644 --- a/common/cmd_dfu.c +++ 
> >>>>> b/common/cmd_dfu.c @@ -55,7 +55,10 @@ static int
> >>>>> do_dfu(cmd_tbl_t *cmdtp, int flag, int argc, char * const
> >>>>> argv[]) goto done; }
> >>>>> 
> >>>>> +#ifdef CONFIG_TRATS board_usb_init(); +#endif +
> >>>> In mine opinion this #ifdef shall be removed and each target
> >>>> board using the DFU shall define board_usb_init() at board
> >>>> file.
> >>>> 
> >> 
> >> But this isn't a called-only-once place.  What are you really
> >> doing here and are you sure it's needed every time DFU is
> >> called?
> >> 
> > 
> > Hmm, you are correct here.
> > 
> > But I don't have a good alternative for this.
> > 
> > One solution would be to define a static flag for it at do_dfu
> > function to indicate if this was executed once (however I'm
> > reluctant do this).
> > 
> > 
> > Any ideas?
> 
> I think the answer, and it's what we do on am335x is that
> arch_misc_init() is what calls the equiv of s3c_udc_probe(...) under
> the logic of "if we are built with usb gadget support, we want to use
> it, so init it".

I've understood the policy differently:

"We are build with gadget support and we _might_ use it, so enable low
level code only when (or just before) we use it". 

What's about the power consumption? Why IP block which will
be used from time to time shall be enabled and operational?

> 
> - -- 
> Tom
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> =mdL4
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