From 2e47e84245adcb1b3872210678b6146f674fb3ff Mon Sep 17 00:00:00 2001 From: Kuninori Morimoto Date: Tue, 2 Sep 2014 19:08:53 -0700 Subject: [PATCH] mmc: Add .multi_io_quirk callback for multi I/O HW bug Historically, we have been using MMC_CAP* to handle host HW issues and currently the block layer uses MMC_CAP2_NO_MULTI_READ flag for a multi I/O HW bug workaround. There are a few tweaks needed to make MMC_CAP2_NO_MULTI_READ suite all situations. Therefore let's add an optional host ops callback to enable host drivers to return the number of blocks it allows per request. In a future patch and when host drivers have converted to the new callback, MMC_CAP2_NO_MULTI_READ shall be removed. Signed-off-by: Kuninori Morimoto Signed-off-by: Ulf Hansson --- drivers/mmc/card/block.c | 10 ++++++++++ include/linux/mmc/host.h | 7 +++++++ 2 files changed, 17 insertions(+) diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c index ede41f05c392..adab9038f6f7 100644 --- a/drivers/mmc/card/block.c +++ b/drivers/mmc/card/block.c @@ -1402,6 +1402,16 @@ static void mmc_blk_rw_rq_prep(struct mmc_queue_req *mqrq, if (card->host->caps2 & MMC_CAP2_NO_MULTI_READ && rq_data_dir(req) == READ) brq->data.blocks = 1; + + /* + * Some controllers have HW issues while operating + * in multiple I/O mode + */ + if (card->host->ops->multi_io_quirk) + brq->data.blocks = card->host->ops->multi_io_quirk(card, + (rq_data_dir(req) == READ) ? + MMC_DATA_READ : MMC_DATA_WRITE, + brq->data.blocks); } if (brq->data.blocks > 1 || do_rel_wr) { diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h index 4cbf61476999..10e2bd6985ae 100644 --- a/include/linux/mmc/host.h +++ b/include/linux/mmc/host.h @@ -139,6 +139,13 @@ struct mmc_host_ops { int (*select_drive_strength)(unsigned int max_dtr, int host_drv, int card_drv); void (*hw_reset)(struct mmc_host *host); void (*card_event)(struct mmc_host *host); + + /* + * Optional callback to support controllers with HW issues for multiple + * I/O. Returns the number of supported blocks for the request. + */ + int (*multi_io_quirk)(struct mmc_card *card, + unsigned int direction, int blk_size); }; struct mmc_card;