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This patch adds a status check after device0 attachment to solve race conditions observed during attachment with multiple devices per link The sequence is the following 1) deviceA attaches as device0 2) the hardware detects a device0 status change and throws an interrupt. 3) the interrupt handler schedules the work function 4) the workqueue starts, we read the status slave0 = cdns_readl(cdns, CDNS_MCP_SLAVE_INTSTAT0); slave1 = cdns_readl(cdns, CDNS_MCP_SLAVE_INTSTAT1); we deal with the status change and program deviceA device number to a non-zero value. 5) deviceB attaches as device0, the device0 status seen by the hardware does not change. 6) we clear the CDNS_MCP_SLAVE_INTSTAT0/1 registers -> we will never detect deviceB! This patch suggest re-checking in a loop the device0 status with a PING frame, i.e. using the real device0 status instead of information on status changes. Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com> Reviewed-by: Rander Wang <rander.wang@intel.com> Signed-off-by: Bard Liao <yung-chuan.liao@linux.intel.com> Link: https://lore.kernel.org/r/20220420023039.14144-1-yung-chuan.liao@linux.intel.com Signed-off-by: Vinod Koul <vkoul@kernel.org>
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.