Re: [RFC PATCH v2] mmc: suspend MMC also when unbinding

[Wolfram Sang <wsa+renesas@sang-engineering.com>]

[-- Attachment #1: Type: text/plain, Size: 1973 bytes --]

On Mon, Nov 04, 2024 at 11:18:42AM +0200, Wolfram Sang wrote:
> When unbinding a MMC host, the card should be suspended. Otherwise,
> problems may arise. E.g. the card still expects power-off notifications
> but there is no host to send them anymore. Shimoda-san tried disabling
> notifications only, but there were issues with his approaches [1] [2].
> 
> Here is my take on it, based on the review comments:
> 
> a) 'In principle we would like to run the similar operations at "remove"
>     as during "system suspend"' [1]
> b) 'We want to support a graceful power off sequence or the card...' [2]
> 
> So, first, mmc_remove_card() gets improved to mark the card as "not
> present" and to call the bus specific suspend() handler.
> 
> Then, _mmc_suspend gets extended to recognize another reason of being
> called, namely when a card removal happens. Building upon the now
> updated mmc_remove_card(), this is the case when the card is flagged as
> "not present".
> 
> The logic of either sending a notification or sending the card to sleep
> gets updated to handle this new reason. Controllers able to do full
> power cycles will still do a full power cycle. Controllers which can
> only do power cycles in suspend, will send the card to sleep.
> 
> All this is for MMC. SD/SDIO are unaffected because they are not using
> the 'card present' flag.
> 
> Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
> 
> [1] https://patchwork.kernel.org/project/linux-renesas-soc/patch/1602581312-23607-1-git-send-email-yoshihiro.shimoda.uh@renesas.com/
> [2] https://patchwork.kernel.org/project/linux-mmc/patch/1605005330-7178-1-git-send-email-yoshihiro.shimoda.uh@renesas.com/
> ---
> 
> Lightly tested with a Renesas R-Car S4 Spider board. It bascially works
> as expected. Serious testing postponed until the generic direction of
> this is approved :)

Anything I can do to make the review easier? Some more testing maybe?


[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 833 bytes --]