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0c5e99c415
The correct way to handle interrupts is to clear the bits we are about to handle _before_ handling them. Thus if the condition then re-asserts during the handling we won't lose it. This patch changes cdns_update_slave_status_work() to do this. The previous code cleared the interrupts after handling them. The problem with this is that when handling enumeration of devices the ATTACH statuses can be accidentally cleared and so some or all of the devices never complete their enumeration. Thus we can have a situation like this: - one or more devices are reverting to ID #0 - accumulated status bits indicate some devices attached and some on ID #0. (Remember: status bits are sticky until they are handled) - Because of device on #0 sdw_handle_slave_status() programs the device ID and exits without handling the other status, expecting to get an ATTACHED from this reprogrammed device. - The device immediately starts reporting ATTACHED in PINGs, which will assert its CDNS_MCP_SLAVE_INTSTAT_ATTACHED bit. - cdns_update_slave_status_work() clears INTSTAT0/1. If the initial status had CDNS_MCP_SLAVE_INTSTAT_ATTACHED bit set it will be cleared. - The ATTACHED change for the device has now been lost. - cdns_update_slave_status_work() clears CDNS_MCP_INT_SLAVE_MASK so if the new ATTACHED state had set it, it will be cleared without ever having been handled. Unless there is some other state change from another device to cause a new interrupt, the ATTACHED state of the reprogrammed device will never cause an interrupt so its enumeration will not be completed. Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com> Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com> Link: https://lore.kernel.org/r/20220914160248.1047627-5-rf@opensource.cirrus.com Signed-off-by: Vinod Koul <vkoul@kernel.org> |
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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.