Rob, On Wed, Jun 8, 2016 at 1:19 PM, Rob Herring <robh@xxxxxxxxxx> wrote: > On Tue, Jun 07, 2016 at 03:44:39PM -0700, Douglas Anderson wrote: >> Some SD/eMMC PHYs (like the PHY from Arasan that is designed to work >> with arasan,sdhci-5.1) need to know the card clock in order to function >> properly. Let's expose this clock using a standard device tree >> mechanism so that the PHY can get access to and query the card clock. > > Need to know the clock freq or need the clock? The former doesn't need > to be in DT. The PHY needs to know the card clock frequency. This clock clock frequency is known nowhere else in the system except the SDHCI driver since the SDHCI component takes its input clock and applies some dividers to get the card clock. In silicon, the SDHCI component and the PHY are separate and there is a physical clock signal going from the SDHCI component to the PHY component, so modeling this as a clock in in the device tree seems sane, doesn't it? -Doug -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
