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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 <dianders@chromium.org> Signed-off-by: Seungwon Jeon <tgih.jun@samsung.com> Signed-off-by: Chris Ball <cjb@laptop.org>
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1 changed files with 28 additions and 16 deletions
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@ -88,6 +88,9 @@ struct idmac_desc {
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* @queue_node: List node for placing this node in the @queue list of
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* &struct dw_mci.
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* @clock: Clock rate configured by set_ios(). Protected by host->lock.
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* @__clk_old: The last updated clock with reflecting clock divider.
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* Keeping track of this helps us to avoid spamming the console
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* with CONFIG_MMC_CLKGATE.
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* @flags: Random state bits associated with the slot.
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* @id: Number of this slot.
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* @last_detect_state: Most recently observed card detect state.
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@ -105,6 +108,7 @@ struct dw_mci_slot {
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struct list_head queue_node;
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unsigned int clock;
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unsigned int __clk_old;
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unsigned long flags;
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#define DW_MMC_CARD_PRESENT 0
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#define DW_MMC_CARD_NEED_INIT 1
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@ -632,24 +636,31 @@ static void mci_send_cmd(struct dw_mci_slot *slot, u32 cmd, u32 arg)
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static void dw_mci_setup_bus(struct dw_mci_slot *slot, bool force_clkinit)
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{
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struct dw_mci *host = slot->host;
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unsigned int clock = slot->clock;
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u32 div;
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u32 clk_en_a;
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if (slot->clock != host->current_speed || force_clkinit) {
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div = host->bus_hz / slot->clock;
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if (host->bus_hz % slot->clock && host->bus_hz > slot->clock)
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if (!clock) {
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mci_writel(host, CLKENA, 0);
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mci_send_cmd(slot,
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SDMMC_CMD_UPD_CLK | SDMMC_CMD_PRV_DAT_WAIT, 0);
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} else if (clock != host->current_speed || force_clkinit) {
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div = host->bus_hz / clock;
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if (host->bus_hz % clock && host->bus_hz > clock)
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/*
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* move the + 1 after the divide to prevent
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* over-clocking the card.
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*/
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div += 1;
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div = (host->bus_hz != slot->clock) ? DIV_ROUND_UP(div, 2) : 0;
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div = (host->bus_hz != clock) ? DIV_ROUND_UP(div, 2) : 0;
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if ((clock << div) != slot->__clk_old || force_clkinit)
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dev_info(&slot->mmc->class_dev,
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"Bus speed (slot %d) = %dHz (slot req %dHz, actual %dHZ"
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" div = %d)\n", slot->id, host->bus_hz, slot->clock,
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div ? ((host->bus_hz / div) >> 1) : host->bus_hz, div);
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"Bus speed (slot %d) = %dHz (slot req %dHz, actual %dHZ div = %d)\n",
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slot->id, host->bus_hz, clock,
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div ? ((host->bus_hz / div) >> 1) :
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host->bus_hz, div);
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/* disable clock */
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mci_writel(host, CLKENA, 0);
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@ -676,9 +687,12 @@ static void dw_mci_setup_bus(struct dw_mci_slot *slot, bool force_clkinit)
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mci_send_cmd(slot,
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SDMMC_CMD_UPD_CLK | SDMMC_CMD_PRV_DAT_WAIT, 0);
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host->current_speed = slot->clock;
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/* keep the clock with reflecting clock dividor */
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slot->__clk_old = clock << div;
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}
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host->current_speed = clock;
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/* Set the current slot bus width */
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mci_writel(host, CTYPE, (slot->ctype << slot->id));
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}
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@ -807,13 +821,11 @@ static void dw_mci_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
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mci_writel(slot->host, UHS_REG, regs);
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if (ios->clock) {
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/*
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* Use mirror of ios->clock to prevent race with mmc
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* core ios update when finding the minimum.
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*/
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slot->clock = ios->clock;
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}
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if (drv_data && drv_data->set_ios)
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drv_data->set_ios(slot->host, ios);
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