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

[Bryan O'Donoghue]

On 03/01/2022 05:51, Manivannan Sadhasivam wrote:
> On Mon, Jan 03, 2022 at 03:03:15AM +0000, 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>
> 
> Can you please CC stable list for backporting?
> 
> Thanks,
> Mani
> 

NP.

+ cc stable

FWIW I believe Greg's scripts will pick up on Fixes: tags automatically