On Wed, Jul 18, 2018 at 11:22 PM, Maxime Ripard <maxime.ripard@xxxxxxxxxxx> wrote: > On Tue, Jul 17, 2018 at 11:43:03PM +0800, Chen-Yu Tsai wrote: >> On Tue, Jul 17, 2018 at 11:15 PM, Maxime Ripard >> <maxime.ripard@xxxxxxxxxxx> wrote: >> > On Thu, Jul 12, 2018 at 06:17:23PM +0800, Chen-Yu Tsai wrote: >> >> On Thu, Jul 12, 2018 at 3:19 PM, Maxime Ripard >> >> <maxime.ripard@xxxxxxxxxxx> wrote: >> >> > Hi, >> >> > >> >> > On Thu, Jul 12, 2018 at 11:02:25AM +0800, Chen-Yu Tsai wrote: >> >> >> The eMMC controller is also a new timing mode controller, but it doesn't >> >> >> have the timing mode switch. It does however have signal delay and >> >> >> calibration controls, typical of Allwinner MMC controllers that support >> >> >> the new timing mode. >> >> >> >> >> >> Enable the new timing mode setting for the A64 eMMC controller. This >> >> >> also enables MMC HS-DDR modes, which gives higher throughput for eMMC >> >> >> chips that support it, and can deliver such throughput. >> >> >> >> >> >> Signed-off-by: Chen-Yu Tsai <wens@xxxxxxxx> >> >> > >> >> > That doesn't look right. The datasheet explicitly mentions that this >> >> > bit doesn't apply to the eMMC controller, and the BSP is doing the same: >> >> > https://github.com/longsleep/linux-pine64/blob/lichee-dev-v3.10.65/drivers/mmc/host/sunxi-mmc-sun50iw1p1-1.c >> >> > >> >> > vs >> >> > https://github.com/longsleep/linux-pine64/blob/lichee-dev-v3.10.65/drivers/mmc/host/sunxi-mmc-sun50iw1p1-2.c >> >> >> >> You mean the bit in SDXC_REG_SD_NTSR? Yes I know that doesn't exist >> >> for the eMMC controller. I mentioned this in the commit message. It >> >> doesn't exist, and writes to it become a no-op. >> >> >> >> Would a comment, or comments, help with making this clear? >> > >> > Ah right. Maybe we should move the calibration under can_calibrate >> > though, or create another boolean for this? >> > >> > Putting it under has_new_timings while the SoC doesn't use it looks >> > very confusing. >> >> IIRC we don't support calibration anyway. This boolean simply signals >> the usage of the new timing mode, whether by choice, or because it is >> the only mode the controller supports. > > This is not the semantic I had in mind when I introduced it. The > original intent was to set the new timing bit all the time for > SoCs. If we want to change that semantic, then we also need to make > sure what this bit means is documented properly. In the driver: /* hardware only supports new timing mode */ bool needs_new_timings; /* hardware can switch between old and new timing modes */ bool has_timings_switch; So if the A64 / H6 eMMC controller only supports / is stuck with the new timing mode, that surely fits the description of the first one, right? As for setting the new timing bit all the time, yes it is set, but it's a no-op. Would a comment clarifying this at the point the hardware bit is set suffice? Thanks ChenYu -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
