From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chen-Yu Tsai Subject: [PATCH RFC 03/15] mmc: sunxi: Block signal voltage switching (CMD11) Date: Thu, 21 Jan 2016 13:26:30 +0800 Message-ID: <1453354002-28366-4-git-send-email-wens@csie.org> References: <1453354002-28366-1-git-send-email-wens@csie.org> Return-path: In-Reply-To: <1453354002-28366-1-git-send-email-wens@csie.org> Sender: linux-kernel-owner@vger.kernel.org To: Ulf Hansson , Maxime Ripard Cc: Chen-Yu Tsai , Hans de Goede , linux-mmc@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-sunxi@googlegroups.com List-Id: linux-mmc@vger.kernel.org Allwinner's mmc controller supports signal voltage switching. This is supported in code in Allwinner's kernel. However, publicly available boards all tie it to a fixed 3.0/3.3V regulator, with options to tie it to 1.8V for eMMC on some. Since Allwinner's kernel is an ancient 3.4, it is hard to say whether adapting it's code to a modern mainline kernel would work. Block signal voltage switching until someone has proper hardware to implement and test this. This only affects SD UHS-1 modes, as eMMC switches the voltage directly without any signaling. Signed-off-by: Chen-Yu Tsai --- drivers/mmc/host/sunxi-mmc.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/drivers/mmc/host/sunxi-mmc.c b/drivers/mmc/host/sunxi-mmc.c index 790f01662b4e..0495ae7da6d6 100644 --- a/drivers/mmc/host/sunxi-mmc.c +++ b/drivers/mmc/host/sunxi-mmc.c @@ -816,6 +816,20 @@ static void sunxi_mmc_request(struct mmc_host *mmc, struct mmc_request *mrq) } } + /* + * TODO Support signal voltage switching + * + * Compared to Allwinner's kernel, recent updates in the mmc core + * mean this should be as easy as setting the flags in cmd_val and + * imask, and waiting for it to finish. However no boards support + * this so this cannot be tested. Block it for now. + */ + if (cmd->opcode == SD_SWITCH_VOLTAGE) { + mrq->cmd->error = -EPERM; + mmc_request_done(mmc, mrq); + return; + } + if (cmd->opcode == MMC_GO_IDLE_STATE) { cmd_val |= SDXC_SEND_INIT_SEQUENCE; imask |= SDXC_COMMAND_DONE; -- 2.7.0.rc3