4dad599b8b
The rtsx USB parent device, has logic to detect when a card is inserted into the card slot. Although, the logic can't detect when a card is removed. This makes things a bit tricky, which is why the current method is simply to turn on MMC_CAP_NEEDS_POLL during probe. Using MMC_CAP_NEEDS_POLL means lots of energy being wasted, as the mmc host becomes runtime resumed frequently by the mmc core, while it polls for new cards being inserted. To address this problem, let's start relying on that the rtsx USB driver runtime resumes its child device, which is the rtsx_usb_sdmmc device, when it detects that a new card being inserted. This means dropping MMC_CAP_NEEDS_POLL from being set during probe. Instead let's implement a ->runtime_resume() callback to schedule a detect work and to set MMC_CAP_NEEDS_POLL. In this way, polling is enabled as long as there is card inserted, thus we can rely on the mmc core to detect also when the card becomes removed. Furthermore, to avoid polling forever after a card has been removed, let's implement a ->runtime_suspend() callback and make it clear MMC_CAP_NEEDS_POLL. Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org> Tested-by: Kai-Heng Feng <kai.heng.feng@canonical.com> Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.