5c23b3f965
Interacting with a NAND chip on an IPQ6018 I found that the qcomsmem NAND
partition parser was returning -EPROBE_DEFER waiting for the main smem
driver to load.
This caused the board to reset. Playing about with the probe() function
shows that the problem lies in the core clock being switched off before the
nandc_unalloc() routine has completed.
If we look at how qcom_nandc_remove() tears down allocated resources we see
the expected order is
qcom_nandc_unalloc(nandc);
clk_disable_unprepare(nandc->aon_clk);
clk_disable_unprepare(nandc->core_clk);
dma_unmap_resource(&pdev->dev, nandc->base_dma, resource_size(res),
DMA_BIDIRECTIONAL, 0);
Tweaking probe() to both bring up and tear-down in that order removes the
reset if we end up deferring elsewhere.
Fixes: c76b78d8ec05 ("mtd: nand: Qualcomm NAND controller driver")
Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Reviewed-by: Manivannan Sadhasivam <mani@kernel.org>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20220103030316.58301-2-bryan.odonoghue@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 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.