a115b1bd3a
When the link is in L1, hardware should return it to L0 automatically whenever a transaction targets a component on the other end of the link (PCIe r5.0, sec 5.2). The R-Car PCIe controller doesn't handle this transition correctly. If the link is not in L0, an MMIO transaction targeting a downstream device fails, and the controller reports an ARM imprecise external abort. Work around this by hooking the abort handler so the driver can detect this situation and help the hardware complete the link state transition. When the R-Car controller receives a PM_ENTER_L1 DLLP from the downstream component, it sets PMEL1RX bit in PMSR register, but then the controller enters some sort of in-between state. A subsequent MMIO transaction will fail, resulting in the external abort. The abort handler detects this condition and completes the link state transition by setting the L1IATN bit in PMCTLR and waiting for the link state transition to complete. Link: https://lore.kernel.org/r/20210815181650.132579-1-marek.vasut@gmail.com Signed-off-by: Marek Vasut <marek.vasut+renesas@gmail.com> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> Cc: Bjorn Helgaas <bhelgaas@google.com> Cc: Geert Uytterhoeven <geert+renesas@glider.be> Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> Cc: Wolfram Sang <wsa@the-dreams.de> Cc: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com> Cc: linux-renesas-soc@vger.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.