On 16 August 2012 22:22, Chris Ball <cjb@xxxxxxxxxx> wrote: > Hi Thomas, > > On Thu, Aug 16 2012, Thomas Abraham wrote: >> +Optional Board Specific Properties: >> +- One of the following properties for card detect type. >> + - samsung,sdhci-cd-internal: Card detect line from the card slot is >> + connected to the card detect pad of the sdhci controller. A gpio is >> + used for this connection (with possible pin function settings). >> + - samsung,sdhci-cd-gpio: A gpio line (with possible pin function settings) >> + is used a card detect line. This gpio line is not connected to card detect >> + pad of the sdhci controller. >> + - samsung,sdhci-cd-none: There is no card detect line. Polling is used to >> + detect the presence of the card. (DEFAULT, if no card detect property >> + is specified). >> + - samsung,sdhci-cd-permanent: There is no card detect line. The card is >> + permanently connected to the sdhci controller. > > sdhci-s3c isn't the only driver that's going to have options for > different cd configurations -- maybe now is the right time to move > these options into the core bindings? Yes, I agree. It will be better to reduce the custom bindings. > > At OLPC we've just started using: > > * "broken-cd" to mean "samsung,sdhci-cd-none", Yes, they are mean the same. > > * the presence of a "cd-gpios" property to imply "samsung,sdhci-cd-gpio". "samsung,sdhci-cd-gpio" and "sdhci-cd-internal" both use the cd-gpio line. "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. > > * "non-removable" to mean "samsung,sdhci-cd-permanent" (this is already > specified in mmc.txt) Ok. > > Would these work for you? Yes, the first and the third works, but the second point needs a way to identify the type of external card-detection mechanism. > > We don't have a distinction between sdhci-cd-internal and sdhci-cd-gpio, > and I'm having trouble working out why one is necessary. Why does the > driver need to know where the gpio came from, aside from knowing which > gpio it is and whether it needs to be inverted (with cd-inverted)? This is as explained above. Maybe other controllers also need something similar to "samsung,sdhci-cd-gpio" and "sdhci-cd-internal". And so, we could make a generic binding for these as well. Thanks, Thomas. -- 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
