On Sat, 14 Sept 2024 at 13:52, Heiko Stübner <heiko@xxxxxxxxx> wrote:
Am Donnerstag, 12. September 2024, 09:26:14 CEST schrieb Kever Yang:
In order to make the SD card hotplug working we need the card detect
function logic inside the controller always working. The runtime PM will
gate the clock and the power domain, which stops controller working when
no data transfer happen.
So lets skip enable runtime PM when the card needs to detected by the
controller and the card is removable.
Signed-off-by: Kever Yang <kever.yang@xxxxxxxxxxxxxx>
So for the change itself this looks good, i.e. it fixes an issue for baords relying
on the on-chip-card-detect.
But for boards doing that, the controller will be running _all the time_
even if there is never any card inserted.
So relying on the on-soc card-detect will effectively increase the power-
consumption of the board - even it it'll never use any sd-card?
Good point! A better option is to use a polling based mechanism - and
we have MMC_CAP_NEEDS_POLL for exactly that.
Moreover, on DT based platforms one can even use the "broken-cd"
property to indicate this.
[...]
Kind regards
Uffe
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