On Mon, 19 Apr 2010 09:34:42 +0800, "Zou, Nanhai" <[email protected]> wrote: > >>-----Original Message----- > >>From: Anholt, Eric > >>Sent: 2010年4月13日 2:29 > >>To: Zou, Nanhai; [email protected] > >>Subject: Re: [Intel-gfx] [Patch 5/5] multiple ring buffer support, fix a irq > >>enable logic for BSD > >> > >>On Wed, 7 Apr 2010 14:28:39 +0800, "Zou, Nanhai" <[email protected]> > >>wrote: > >>> Fix the BSD ring related IRQ logic on Ironlake. > >>> Without this patch, we sometimes see IRQ lost > >>> When playing H.264 content. > >> > >>This patch looks crazy. Why do we need to do this? How did you come up > >>with it? What prevents races between IIR clear and IER or IMR enable (if > >>that's what the IIR clear is about). > >> > > Yes, it looks a little strange. > However HW spec from VCG do says IIR should be cleared before enable and > disable interrupt. > We thought this patch fixed the interrupt lost issue seen when playing movie. > But now we found it just make the issue much harder to reproduce, so ignore > this patch until we found a real fix.
Before enable, sure, that makes sense -- otherwise you'd trigger an interrupt right away when you know you don't need it. But we do unmasking, not enabling.
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