[PATCH v2 1/2] mtd: rawnand: qcom: Fix clock sequencing in qcom_nandc_probe()

[Miquel Raynal]

On Mon, 2022-01-03 at 03:03:15 UTC, Bryan O'Donoghue wrote:
> 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 at linaro.org>
> Reviewed-by: Manivannan Sadhasivam <mani at kernel.org>

Applied to https://git.kernel.org/pub/scm/linux/kernel/git/mtd/linux.git mtd/next, thanks.

Miquel