On Wed, 10 Nov 2010 08:36:20 +0800, "Zou, Nanhai" <[email protected]> wrote: > >>-----Original Message----- > >>From: Chris Wilson [mailto:[email protected]] > >>Sent: 2010å¹´11æ9æ¥ 18:50 > >>To: Zou, Nanhai; [email protected]; Zhao, Jian J > >>Subject: RE: [PATCH] drm/i915/ringbuffer: set force wake bit before reading > >>ring register > >> > >>On Tue, 9 Nov 2010 17:17:07 +0800, "Zou, Nanhai" <[email protected]> > >>wrote: > >> > >>> I have tested this patch with the read ring head from status page > >>> workaround > >>patch reverted. > >>> Seems it works on my SNB box. > >> > >>I needed to add a udelay(100) to i915_safe_read for my rev 8. Can you > >>check if there is a recommended delay for FORCEWAKE? > >>-Chris > >> > Dose a post read to FORCEWAKE help?
No, tried a POSTING_READ(FORCEWAKE) first and it wasn't until I added the udelay() between the READ(FORCEWAKE) and the READ(reg) that it returned the correct results in a single call. -Chris -- Chris Wilson, Intel Open Source Technology Centre
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