ARM: MXC: mxcmmc: work around a bug in the SDHC busy line handling
MX3 SoCs have a silicon bug which corrupts CRC calculation of multi-block transfers when connected SDIO peripheral doesn't drive the BUSY line as required by the specs. One way to prevent this is to only allow 1-bit transfers. Another way is playing tricks with the DMA engine, but this isn't mainline yet. So for now, we live with the performance drawback of 1-bit transfers until a nicer solution is found. This patch introduces a new host controller callback 'init_card' which is for now only called from mmc_sdio_init_card(). Signed-off-by: Daniel Mack <daniel@caiaq.de> Cc: Sascha Hauer <s.hauer@pengutronix.de> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Volker Ernst <volker.ernst@txtr.com> Cc: Jiri Kosina <jkosina@suse.cz> Cc: Michał Mirosław <mirqus@gmail.com> Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
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@ -295,6 +295,12 @@ static int mmc_sdio_init_card(struct mmc_host *host, u32 ocr,
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card->type = MMC_TYPE_SDIO;
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/*
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* Call the optional HC's init_card function to handle quirks.
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*/
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if (host->ops->init_card)
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host->ops->init_card(host, card);
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/*
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* For native busses: set card RCA and quit open drain mode.
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*/
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@ -724,11 +724,27 @@ static void mxcmci_enable_sdio_irq(struct mmc_host *mmc, int enable)
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spin_unlock_irqrestore(&host->lock, flags);
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}
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static void mxcmci_init_card(struct mmc_host *host, struct mmc_card *card)
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{
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/*
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* MX3 SoCs have a silicon bug which corrupts CRC calculation of
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* multi-block transfers when connected SDIO peripheral doesn't
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* drive the BUSY line as required by the specs.
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* One way to prevent this is to only allow 1-bit transfers.
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*/
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if (cpu_is_mx3() && card->type == MMC_TYPE_SDIO)
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host->caps &= ~MMC_CAP_4_BIT_DATA;
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else
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host->caps |= MMC_CAP_4_BIT_DATA;
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}
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static const struct mmc_host_ops mxcmci_ops = {
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.request = mxcmci_request,
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.set_ios = mxcmci_set_ios,
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.get_ro = mxcmci_get_ro,
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.enable_sdio_irq = mxcmci_enable_sdio_irq,
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.init_card = mxcmci_init_card,
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};
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static int mxcmci_probe(struct platform_device *pdev)
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@ -108,6 +108,9 @@ struct mmc_host_ops {
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int (*get_cd)(struct mmc_host *host);
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void (*enable_sdio_irq)(struct mmc_host *host, int enable);
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/* optional callback for HC quirks */
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void (*init_card)(struct mmc_host *host, struct mmc_card *card);
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};
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struct mmc_card;
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