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The dwc3 driver can overwite its previous events if its top-half IRQ handler (TH) gets invoked again before processing the events in the cache. We see this as a hang in the file transfer and the host will attempt to reset the device. TH gets the event count and deasserts the interrupt line by writing DWC3_GEVNTSIZ_INTMASK to DWC3_GEVNTSIZ. If there's a new event coming between reading the event count and interrupt deassertion, dwc3 will lose previous pending events. More generally, we will see 0 event count, which should not affect anything. This shouldn't be possible in the current dwc3 implementation. However, through testing and reading the PCIe trace, the TH occasionally still gets invoked one more time after HW interrupt deassertion. (With PCIe legacy interrupts, TH is called repeatedly as long as the interrupt line is asserted). We suspect that there is a small detection delay in the SW. To avoid this issue, Check DWC3_EVENT_PENDING flag to determine if the events are processed in the bottom-half IRQ handler. If not, return IRQ_HANDLED and don't process new event. Cc: stable@vger.kernel.org Signed-off-by: Thinh Nguyen <thinhn@synopsys.com> Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. 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.