From 93b6911ac1ffc1fc9aba92c9e19063d47e7cf236 Mon Sep 17 00:00:00 2001 From: Wolfram Sang Date: Fri, 1 Apr 2016 17:44:36 +0200 Subject: [PATCH] mmc: host: add note that set_ios needs to handle 0Hz properly While here, refactor the comments so that they are before the declaration they are referring to. Signed-off-by: Wolfram Sang Signed-off-by: Ulf Hansson --- include/linux/mmc/host.h | 31 +++++++++++++++++++++---------- 1 file changed, 21 insertions(+), 10 deletions(-) diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h index 8dd4d290ab0d..85800b48241f 100644 --- a/include/linux/mmc/host.h +++ b/include/linux/mmc/host.h @@ -93,28 +93,39 @@ struct mmc_host_ops { void (*pre_req)(struct mmc_host *host, struct mmc_request *req, bool is_first_req); void (*request)(struct mmc_host *host, struct mmc_request *req); + + /* + * Avoid calling the next three functions too often or in a "fast + * path", since underlaying controller might implement them in an + * expensive and/or slow way. Also note that these functions might + * sleep, so don't call them in the atomic contexts! + */ + + /* + * Notes to the set_ios callback: + * ios->clock might be 0. For some controllers, setting 0Hz + * as any other frequency works. However, some controllers + * explicitly need to disable the clock. Otherwise e.g. voltage + * switching might fail because the SDCLK is not really quiet. + */ + void (*set_ios)(struct mmc_host *host, struct mmc_ios *ios); + /* - * Avoid calling these three functions too often or in a "fast path", - * since underlaying controller might implement them in an expensive - * and/or slow way. - * - * Also note that these functions might sleep, so don't call them - * in the atomic contexts! - * * Return values for the get_ro callback should be: * 0 for a read/write card * 1 for a read-only card * -ENOSYS when not supported (equal to NULL callback) * or a negative errno value when something bad happened - * + */ + int (*get_ro)(struct mmc_host *host); + + /* * Return values for the get_cd callback should be: * 0 for a absent card * 1 for a present card * -ENOSYS when not supported (equal to NULL callback) * or a negative errno value when something bad happened */ - void (*set_ios)(struct mmc_host *host, struct mmc_ios *ios); - int (*get_ro)(struct mmc_host *host); int (*get_cd)(struct mmc_host *host); void (*enable_sdio_irq)(struct mmc_host *host, int enable); -- 2.25.1