linux-kernel - Re: [RESEND/PATCH 5/6] USB: musb-gadget: complete request only if data is transfered over

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Message-ID: <20100914105402.GD7554@legolas.emea.dhcp.ti.com>
Date:	Tue, 14 Sep 2010 13:54:02 +0300
From:	Felipe Balbi <balbi@...com>
To:	Sergei Shtylyov <sshtylyov@...sta.com>
Cc:	"Balbi, Felipe" <balbi@...com>, Ming Lei <tom.leiming@...il.com>,
	"greg@...ah.com" <greg@...ah.com>,
	"linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
	"linux-omap@...r.kernel.org" <linux-omap@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	David Brownell <dbrownell@...rs.sourceforge.net>,
	"Gadiyar, Anand" <gadiyar@...com>,
	Mike Frysinger <vapier@...too.org>
Subject: Re: [RESEND/PATCH 5/6] USB: musb-gadget: complete request only if
 data is transfered over

Hi,

On Tue, Sep 14, 2010 at 05:46:22AM -0500, Sergei Shtylyov wrote:
>    If a DMA interrupt comes when the whole transfer is not yet complete (and
>other Ming Lei's patches are making this possible), it will pass due to the

than this is the actual problem, no ? If we're using mode1 dma (as we
are on tx path), we should only get dma interrupt when the whole
transfer has been completed.

>'ís_dma' condition above the patched code:
>
>                 if (is_dma || request->actual == request->length) {
>
>and then it will hit the code sending the final ZLP (above this patched code too):

but this was already there before the patch.

>                         /*
>                          * First, maybe a terminating short packet. Some DMA
>                          * engines might handle this by themselves.
>                          */
>                         if ((request->zero && request->length
>                                 && request->length % musb_ep->packet_sz == 0)
>#ifdef CONFIG_USB_INVENTRA_DMA
>                                 || (is_dma && (!dma->desired_mode ||
>                                         (request->actual &
>                                                 (musb_ep->packet_sz - 1))))
>#endif
>                         ) {
>
>before the transfer is complete while it should only be hit when and only when
>the whole transfer is complete. The current code doesn't look correct as well
>though, all due to this 'ís_dma' condition. Surely this needs fixing.

likewise, this was there before the patch. I don't think the real
problem lies with this patch, it's been there for a while, don't you
agree ?

the problem is not on the extra if () added below the quoted code,
it's on the quoted code itself, which wasn't changed in any way.

-- 
balbi
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