From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756622Ab3HFV66 (ORCPT ); Tue, 6 Aug 2013 17:58:58 -0400 Received: from mail-ea0-f177.google.com ([209.85.215.177]:48804 "EHLO mail-ea0-f177.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753526Ab3HFV64 (ORCPT ); Tue, 6 Aug 2013 17:58:56 -0400 From: Tomasz Figa To: Doug Anderson Cc: Chris Ball , Olof Johansson , Jaehoon Chung , Seungwon Jeon , James Hogan , Grant Grundler , Alim Akhtar , Abhilash Kesavan , linux-mmc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v4 1/4] mmc: dw_mmc: Invalidate cache of current_speed after suspend/resume Date: Tue, 06 Aug 2013 23:58:49 +0200 Message-ID: <4496642.gd8AClQe6R@flatron> User-Agent: KMail/4.10.5 (Linux/3.10.4-gentoo; KDE/4.10.5; x86_64; ; ) In-Reply-To: <1375825071-20922-2-git-send-email-dianders@chromium.org> References: <1373470926-19314-1-git-send-email-dianders@chromium.org> <1375825071-20922-1-git-send-email-dianders@chromium.org> <1375825071-20922-2-git-send-email-dianders@chromium.org> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tuesday 06 of August 2013 14:37:48 Doug Anderson wrote: > The dw_mmc driver keeps a cache of the current slot->clock in order to > avoid doing a whole lot of work every time set_ios() is called. > However, after suspend/resume the register values are bogus so we need > to ensure that the cached value is invalidated. > > In many cases we got by without this since the core mmc code fiddles > with the clock a lot. If we've got a card present we're probably > running it at something like 50MHz and the core will temporarily > switch us to 400kHz after resume. One case that didn't work (for me) > is the case of having no card in the slot. The slot is initted to > 400kHz at boot time. After suspend/resume the slot thinks it's still > at 400kHz (due to the cache) so doesn't adjust timing. When it tries > to send the command at probe time it just times out and gets left in a > bad state. > > Invalidating the current_speed also means that we don't need to call: > dw_mci_setup_bus(slot, true); > ...to force an update of the clock in the case when the slot was left > powered. > > Signed-off-by: Doug Anderson > --- > Changes in v4: None > Changes in v3: None > Changes in v2: > - Fix typo (some -> come) > - Use ~0 instead of 0xFFFFFFFF; add comment about value > > drivers/mmc/host/dw_mmc.c | 8 +++++++- > 1 file changed, 7 insertions(+), 1 deletion(-) > > diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c > index ee5f167..13a363c 100644 > --- a/drivers/mmc/host/dw_mmc.c > +++ b/drivers/mmc/host/dw_mmc.c > @@ -2511,13 +2511,19 @@ int dw_mci_resume(struct dw_mci *host) > DW_MCI_ERROR_FLAGS | SDMMC_INT_CD); > mci_writel(host, CTRL, SDMMC_CTRL_INT_ENABLE); > > + /* > + * Invalidate the 'current_speed' value since CLKDIV has come up in > + * default state and our cache is incorrect; set to something we know > + * slot->clock won't be. > + */ > + host->current_speed = ~0; > + > for (i = 0; i < host->num_slots; i++) { > struct dw_mci_slot *slot = host->slot[i]; > if (!slot) > continue; > if (slot->mmc->pm_flags & MMC_PM_KEEP_POWER) { > dw_mci_set_ios(slot->mmc, &slot->mmc->ios); > - dw_mci_setup_bus(slot, true); > } > > ret = mmc_resume_host(host->slot[i]->mmc); Reviewed-by: Tomasz Figa Best regards, Tomasz