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Julius Werner authored
The problem with SD cards is that you need to keep track of removals and reinsertions so that you know when you have to fully reinitialize it. In depthcharge, we do that by maintaining a 'present' member in the MMC controller object. On every update() call to the controller, we check if the previously known 'present' state still matches the current card_detect pin value, and if it doesn't we handle the respective insertion or removal. This works fine in recovery mode: vboot keeps checking for new media automatically every second, so we regularly call update() on all our removable block device controllers. But in dev mode, vboot only asks us to do that when it reads an explicit Ctrl+U from the user. This creates a problem when the user inserts an SD card with an invalid image, presses Ctrl+U (vboot sees that the image is invalid and beeps), replaces the SD card with a different one and presses Ctrl+U again. We only call update() twice on the block device controller in this case, and in both cases there is a card present. The driver has no chance to notice that it is no longer the same card and has to be reinitialized. It's hard to solve this in a good way: we could make it the responsibility of the individual MMC controller driver to track this (through some sort of controller-internal hardware latch), but it's unclear whether all controllers could support that, and it would have to be fixed in every single controller driver individually. We could also change the vboot API to add an explicit polling function that tells depthcharge to update this state, but that seems overkill at a time where we're thinking about moving away from depthcharge at some point anyway (towards a solution that probably wouldn't have this problem). This patch implements the quick and dirty fix of updating removable block device controllers in the only continuously polled vboot callback we have in dev mode, which is VbExKeyboardRead(). It's not exactly a clean solution from a design standpoint, but it'll work. USB storage devices essentially get the same treatment already because libpayload unconditionally calls usb_poll() as part of havechar()... so it's not really any worse than what we already have, just in a different place. BRANCH=oak,gru,nyan,veyron,reef? BUG=b:35854317 TEST=Boot an Elm, plug in a uSD card without a good image, press Ctrl+U, replace SD card with one that has a good image, press Ctrl+U again, watch it boot. Change-Id: I729a37028140f354478422078804e750079a4c23 Signed-off-by: Julius Werner <jwerner@chromium.org> Reviewed-on: https://chromium-review.googlesource.com/750321 Reviewed-by: Aaron Durbin <adurbin@chromium.org> Reviewed-by: Furquan Shaikh <furquan@chromium.org> (cherry picked from commit 6b4baa85) Reviewed-on: https://chromium-review.googlesource.com/753861 Commit-Queue: Aaron Durbin <adurbin@chromium.org> Tested-by: Aaron Durbin <adurbin@chromium.org>
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