Hi, On Tue, Aug 21 2012, Rob Herring wrote: >> cd-gpios and cd-external can be present on the same node. if broken-cd >> is present, it must be the only one of these nodes used. > > I don't see the point of cd-external. Either you just use the CD > interrupt defined within the SDHCI or you have a gpio line independent > of the SDHCI and use cd-gpios. You've described two of the possible cases, but not the third. In the third case, you have a gpio line that is not independent of the SDHCI, because it is the SDHCI's CD pin brought out to be directly accessible via a GPIO. The difference is in the handling of the interrupt -- if you don't have "cd-external" then you're just using the SDHCI's interrupt, but if you have an independent line then you're going to need to register your own IRQ handler on it, and "cd-external" signifies that. Thomas wrote this explanation earlier in the thread: > "samsung,sdhci-cd-gpio" means that the cd-gpio line is not connected > to the card-detect pad of the sdhci controller. Instead, it identifies > cd-gpio as a gpio pin, connected to the card-detect pin of the "card > slot" and it can used as a source of external interrupt. The driver > can register card insert/remove handler for this interrupt and get > notified about the changes in card state. > > "sdhci-cd-internal" means that the "cd-gpio" line is used to connect > the card-detect pin of the card slot and the card-detect pad of the > sdhci controller. The controller is then aware of any changes in card > state and the controller generates appropriate interrupts to notify > changes in card-state. Thanks, - Chris. -- Chris Ball <cjb@xxxxxxxxxx> <http://printf.net/> One Laptop Per Child -- 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
