From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Bresticker Subject: Re: [PATCH 2/4] mmc: tegra: fix reporting of base clock frequency Date: Tue, 15 Apr 2014 12:36:07 -0700 Message-ID: References: <1397526163-20126-1-git-send-email-abrestic@chromium.org> <1397526163-20126-3-git-send-email-abrestic@chromium.org> <534D797D.7030201@wwwdotorg.org> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Return-path: In-Reply-To: <534D797D.7030201-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org> Sender: linux-tegra-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Stephen Warren Cc: Thierry Reding , Chris Ball , Ulf Hansson , "linux-mmc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, "linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org" , "linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" List-Id: linux-mmc@vger.kernel.org On Tue, Apr 15, 2014 at 11:25 AM, Stephen Warren wrote: > On 04/14/2014 07:42 PM, Andrew Bresticker wrote: >> Tegra SDHCI controllers, by default, report a base clock frequency >> of 208Mhz in SDHCI_CAPABILTIES which may or may not be equal to the >> actual base clock frequency. > > Some explanation of why this "may or may not be equal to the actual base > clock frequency" would be nice. > > Presumably, it's because the clock frequency is supplied by the clock > controller module, and configuring that happens externally to the SD > controller, so the SD HW has no knowledge of the actual frequency, and > hence simply reports a hard-coded maximum possible clock frequency? Correct. I'll fix up the commit message. > >> While this can be overridden by setting >> BASE_CLK_FREQ in VENDOR_CLOCK_CTRL on Tegra30 and later SoCs, just >> set SDHCI_QUIRK_CAP_CLOCK_BASE_BROKEN and supply a get_max_clock() >> callback to get the actual rate of the base clock. > > It's not clear to me from the function name that > sdhci_pltfm_clk_get_max_clock() simply calls clk_get() on the actual > clock. It might be nice to mention that in the commit description.