From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ben Widawsky Subject: Re: [PATCH 3/3] drm/i915: go back to switch for VLV mem freq detection Date: Wed, 1 May 2013 18:40:22 -0700 Message-ID: <20130502014021.GA1229@bwidawsk.net> References: <1367449762-2214-1-git-send-email-jbarnes@virtuousgeek.org> <1367449762-2214-3-git-send-email-jbarnes@virtuousgeek.org> <20130502012628.GA9668@bwidawsk.net> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from shiva.localdomain (unknown [209.20.75.48]) by gabe.freedesktop.org (Postfix) with ESMTP id 147F9E5C52 for ; Wed, 1 May 2013 18:37:48 -0700 (PDT) Content-Disposition: inline In-Reply-To: <20130502012628.GA9668@bwidawsk.net> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: intel-gfx-bounces+gcfxdi-intel-gfx=m.gmane.org@lists.freedesktop.org Errors-To: intel-gfx-bounces+gcfxdi-intel-gfx=m.gmane.org@lists.freedesktop.org To: Jesse Barnes Cc: intel-gfx@lists.freedesktop.org List-Id: intel-gfx@lists.freedesktop.org On Wed, May 01, 2013 at 06:26:28PM -0700, Ben Widawsky wrote: > On Wed, May 01, 2013 at 04:09:22PM -0700, Jesse Barnes wrote: > > We need to catch the invalid case and override it. > > > > Signed-off-by: Jesse Barnes > > --- > > drivers/gpu/drm/i915/intel_pm.c | 16 +++++++++++++++- > > 1 file changed, 15 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c > > index 0f4b46e..0a3b0b3 100644 > > --- a/drivers/gpu/drm/i915/intel_pm.c > > +++ b/drivers/gpu/drm/i915/intel_pm.c > > @@ -2902,7 +2902,21 @@ static void valleyview_enable_rps(struct drm_device *dev) > > GEN7_RC_CTL_TO_MODE); > > > > valleyview_punit_read(dev_priv, PUNIT_REG_GPU_FREQ_STS, &val); > > - dev_priv->mem_freq = 800 + (266 * (val >> 6) & 3); > > + switch ((val >> 6) & 3) { > > + case 0: > > + dev_priv->mem_freq = 800; > > + break; > > + case 1: > > + dev_priv->mem_freq = 1066; > > + break; > > + case 2: > > + dev_priv->mem_freq = 1333; > > + break; > > + case 3: > > + DRM_ERROR("invalid mem freq, assuming 800MHz\n"); > > + dev_priv->mem_freq = 800; > > + break; > > + } > > DRM_DEBUG_DRIVER("DDR speed: %d MHz", dev_priv->mem_freq); > > > > DRM_DEBUG_DRIVER("GPLL enabled? %s\n", val & 0x10 ? "yes" : "no"); > > > I guess it doesn't handle the last case, but: > dev_priv->mem_freq = 800 + (266 * (val))) + val/2 > conveniently, I've given you the reason not to use this one... error prone. It's missing a: val = (val >> 6) & 3 before the math. > or > > u32 freqs[] = {800,1066,1333,800}; > dev_priv->mem_freq = freqs[(val >> 6) & 3]; > > Are two ways I would have used before making a switch block :P > > Just a thought, but perhaps we don't want to enable RPS if we can't > reliably figure out the memory freq. (case 3) > > Reviewed-by: Ben Widawsky > > -- > Ben Widawsky, Intel Open Source Technology Center > _______________________________________________ > Intel-gfx mailing list > Intel-gfx@lists.freedesktop.org > http://lists.freedesktop.org/mailman/listinfo/intel-gfx -- Ben Widawsky, Intel Open Source Technology Center