From mboxrd@z Thu Jan 1 00:00:00 1970 From: maxime.ripard@bootlin.com (Maxime Ripard) Date: Fri, 7 Sep 2018 10:14:49 +0200 Subject: [PATCH] mmc: sunxi: Clarify new timing mode usage and implementation In-Reply-To: <20180906153107.20225-1-wens@csie.org> References: <20180906153107.20225-1-wens@csie.org> Message-ID: <20180907081449.roowspmgmtd5zcs6@flea> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Thu, Sep 06, 2018 at 11:31:07PM +0800, Chen-Yu Tsai wrote: > Newer sunxi mmc controller variants support what they call the "new > timing mode". Support for this was implemented in two ways, according > to the hardware that was seen at the time. > > The first type retained the old timing mode, and both the clock and mmc > controllers had switches to select which mode was used. Both switches > had to be set to the same setting. This variant was denoted with the > .has_timings_switch field in the sunxi_mmc_cfg structure. This hardware > is only seen on the A83T. > > The second type did away with the old timing mode. The clock controller > no longer had the mode selection or clock delay setting bits. In some > cases the mmc controller retained its mode selection bit, but this > always needed to be set to the new mode, or instabilities would occur. > In a few cases, such as the A64 and H6 eMMC controller, the mode > selection bit is gone, but the controller still behaves like the new > timing mode, requiring the module clock to be double the card clock > in DDR transfer modes. This variant is denoted with the > .needs_new_timings field. > > This patch adds more comments explaining the two fields, as well as > the possibly nonexistent mode switch in the mmc controller. > > The .has_timings_switch is renamed to .ccu_has_timings_switch to clarify > its meaning. > > Signed-off-by: Chen-Yu Tsai Acked-by: Maxime Ripard Thanks! Maxime -- Maxime Ripard, Bootlin Embedded Linux and Kernel engineering https://bootlin.com -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 833 bytes Desc: not available URL: