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NXP ESDHC supports control of native emmc reset signal when pinmux is set accordingly, using uSDHCx_SYS_CTRL register IPP_RST_N bit. Documentation is available in NXP i.MX6Q Reference Manual. Implement the hw_reset function in sdhci_ops asserting reset for at least 1us and waiting at least 200us after deassertion. Lower bounds are based on: JEDEC Standard No. 84-B51, 6.15.10 H/W Reset Operation, page 159. Upper bounds are chosen allowing flexibility to the scheduler. Tested on SolidRun i.MX8DXL SoM with a scope, and confirmed that eMMC is still accessible after boot: - eMMC extcsd has RST_N_FUNCTION=0x01 - sdhc node has cap-mmc-hw-reset - pinmux set for EMMC0_RESET_B - Linux v5.15 Signed-off-by: Josua Mayer <josua@solid-run.com> Reviewed-by: Haibo Chen <haibo.chen@nxp.com> Acked-by: Adrian Hunter <adrian.hunter@intel.com> Message-ID: <20241101-imx-emmc-reset-v3-1-184965eed476@solid-run.com> Signed-off-by: Ulf Hansson <ulf.hansson@linaro.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 reStructuredText 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.