From: Doug Anderson Date: Fri, 30 Aug 2013 15:11:43 +0000 (+0900) Subject: mmc: dw_mmc: Honor requests to set the clock to 0 X-Git-Tag: v3.13-rc1~50^2~103 X-Git-Url: http://git.cascardo.info/?p=cascardo%2Flinux.git;a=commitdiff_plain;h=fdf492a1cc6db8c13f650948f43855a077600895 mmc: dw_mmc: Honor requests to set the clock to 0 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 situation: * mmc core would set clk to 400kHz at boot time while scanning * 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 Signed-off-by: Seungwon Jeon Signed-off-by: Chris Ball --- diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c index 7192f89b15ae..bc3a430ba027 100644 --- a/drivers/mmc/host/dw_mmc.c +++ b/drivers/mmc/host/dw_mmc.c @@ -88,6 +88,9 @@ struct idmac_desc { * @queue_node: List node for placing this node in the @queue list of * &struct dw_mci. * @clock: Clock rate configured by set_ios(). Protected by host->lock. + * @__clk_old: The last updated clock with reflecting clock divider. + * Keeping track of this helps us to avoid spamming the console + * with CONFIG_MMC_CLKGATE. * @flags: Random state bits associated with the slot. * @id: Number of this slot. * @last_detect_state: Most recently observed card detect state. @@ -105,6 +108,7 @@ struct dw_mci_slot { struct list_head queue_node; unsigned int clock; + unsigned int __clk_old; unsigned long flags; #define DW_MMC_CARD_PRESENT 0 #define DW_MMC_CARD_NEED_INIT 1 @@ -632,24 +636,31 @@ static void mci_send_cmd(struct dw_mci_slot *slot, u32 cmd, u32 arg) static void dw_mci_setup_bus(struct dw_mci_slot *slot, bool force_clkinit) { struct dw_mci *host = slot->host; + unsigned int clock = slot->clock; u32 div; u32 clk_en_a; - 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) + if (!clock) { + mci_writel(host, CLKENA, 0); + mci_send_cmd(slot, + SDMMC_CMD_UPD_CLK | SDMMC_CMD_PRV_DAT_WAIT, 0); + } else if (clock != host->current_speed || force_clkinit) { + div = host->bus_hz / clock; + if (host->bus_hz % clock && host->bus_hz > clock) /* * move the + 1 after the divide to prevent * over-clocking the card. */ div += 1; - div = (host->bus_hz != slot->clock) ? DIV_ROUND_UP(div, 2) : 0; + div = (host->bus_hz != clock) ? DIV_ROUND_UP(div, 2) : 0; - dev_info(&slot->mmc->class_dev, - "Bus speed (slot %d) = %dHz (slot req %dHz, actual %dHZ" - " div = %d)\n", slot->id, host->bus_hz, slot->clock, - div ? ((host->bus_hz / div) >> 1) : host->bus_hz, div); + if ((clock << div) != slot->__clk_old || force_clkinit) + dev_info(&slot->mmc->class_dev, + "Bus speed (slot %d) = %dHz (slot req %dHz, actual %dHZ div = %d)\n", + slot->id, host->bus_hz, clock, + div ? ((host->bus_hz / div) >> 1) : + host->bus_hz, div); /* disable clock */ mci_writel(host, CLKENA, 0); @@ -676,9 +687,12 @@ static void dw_mci_setup_bus(struct dw_mci_slot *slot, bool force_clkinit) mci_send_cmd(slot, SDMMC_CMD_UPD_CLK | SDMMC_CMD_PRV_DAT_WAIT, 0); - host->current_speed = slot->clock; + /* keep the clock with reflecting clock dividor */ + slot->__clk_old = clock << div; } + host->current_speed = clock; + /* Set the current slot bus width */ mci_writel(host, CTYPE, (slot->ctype << slot->id)); } @@ -807,13 +821,11 @@ 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);