Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753639Ab3HVQtZ (ORCPT ); Thu, 22 Aug 2013 12:49:25 -0400 Received: from mail-qe0-f74.google.com ([209.85.128.74]:38678 "EHLO mail-qe0-f74.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753388Ab3HVQtX (ORCPT ); Thu, 22 Aug 2013 12:49:23 -0400 From: Doug Anderson To: Chris Ball Cc: Jaehoon Chung , Seungwon Jeon , James Hogan , Grant Grundler , Alim Akhtar , Abhilash Kesavan , Tomasz Figa , Olof Johansson , Doug Anderson , linux-mmc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v6 2/3] mmc: dw_mmc: Honor requests to set the clock to 0 (turn off clock) Date: Thu, 22 Aug 2013 09:19:07 -0700 Message-Id: <1377188348-3418-3-git-send-email-dianders@chromium.org> X-Mailer: git-send-email 1.8.3 In-Reply-To: <1377188348-3418-1-git-send-email-dianders@chromium.org> References: <1377188348-3418-1-git-send-email-dianders@chromium.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2865 Lines: 78 Previously the dw_mmc driver would ignore any requests to disable the card's clock. This doesn't seem like a good thing in general, but had one extra bad side effect in the following situtation: * mmc core would set clk to 400kHz at boot time while initting * mmc core would set clk to 0 since no card, but it would be ignored. * suspend to ram and resume; clocks in the dw_mmc IP block are now 0 but dw_mmc thinks that they're 400kHz (it ignored the set to 0). * insert card * mmc core would set clk to 400kHz which would be considered a no-op. Note that if there is no card in the slot and we do a suspend/resume cycle, we _do_ still end up with differences in a dw_mmc register dump, but the differences are clock related and we've got the clock disabled both before and after, so this should be OK. Signed-off-by: Doug Anderson --- Changes in v6: - Replaces previous pathes that ensured saving/restoring clocks. drivers/mmc/host/dw_mmc.c | 21 +++++++++++---------- 1 file changed, 11 insertions(+), 10 deletions(-) diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c index ee5f167..f6c7545 100644 --- a/drivers/mmc/host/dw_mmc.c +++ b/drivers/mmc/host/dw_mmc.c @@ -635,7 +635,11 @@ static void dw_mci_setup_bus(struct dw_mci_slot *slot, bool force_clkinit) u32 div; u32 clk_en_a; - if (slot->clock != host->current_speed || force_clkinit) { + if (slot->clock == 0) { + mci_writel(host, CLKENA, 0); + mci_send_cmd(slot, + SDMMC_CMD_UPD_CLK | SDMMC_CMD_PRV_DAT_WAIT, 0); + } else if (slot->clock != host->current_speed || force_clkinit) { div = host->bus_hz / slot->clock; if (host->bus_hz % slot->clock && host->bus_hz > slot->clock) /* @@ -675,9 +679,8 @@ static void dw_mci_setup_bus(struct dw_mci_slot *slot, bool force_clkinit) /* inform CIU */ mci_send_cmd(slot, SDMMC_CMD_UPD_CLK | SDMMC_CMD_PRV_DAT_WAIT, 0); - - host->current_speed = slot->clock; } + host->current_speed = slot->clock; /* Set the current slot bus width */ mci_writel(host, CTYPE, (slot->ctype << slot->id)); @@ -807,13 +810,11 @@ static void dw_mci_set_ios(struct mmc_host *mmc, struct mmc_ios *ios) mci_writel(slot->host, UHS_REG, regs); - if (ios->clock) { - /* - * Use mirror of ios->clock to prevent race with mmc - * core ios update when finding the minimum. - */ - slot->clock = ios->clock; - } + /* + * Use mirror of ios->clock to prevent race with mmc + * core ios update when finding the minimum. + */ + slot->clock = ios->clock; if (drv_data && drv_data->set_ios) drv_data->set_ios(slot->host, ios); -- 1.8.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/