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?
At OLPC we've just started using:
* "broken-cd" to mean "samsung,sdhci-cd-none",
* the presence of a "cd-gpios" property to imply "samsung,sdhci-cd-gpio".
* "non-removable" to mean "samsung,sdhci-cd-permanent" (this is already
specified in mmc.txt)
Would these work for you?
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)?
Thanks,
- Chris.
--
Chris Ball [off-list ref] <http://printf.net/>
One Laptop Per Child
On 16 August 2012 22:22, Chris Ball [off-list ref] wrote:
Hi Thomas,
On Thu, Aug 16 2012, Thomas Abraham wrote:
quoted
+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.