FAILED: patch "[PATCH] mtd: rawnand: qcom: Fix clock sequencing in" failed to apply to 4.9-stable tree

The patch below does not apply to the 4.9-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 5c23b3f965bc9ee696bf2ed4bdc54d339dd9a455 Mon Sep 17 00:00:00 2001
From: Bryan O'Donoghue <[email protected]>
Date: Mon, 3 Jan 2022 03:03:15 +0000
Subject: [PATCH] mtd: rawnand: qcom: Fix clock sequencing in
qcom_nandc_probe()

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.

index 7c6efa3b6255..1a77542c6d67 100644
@@ -2,7 +2,6 @@
 /*
  * Copyright (c) 2016, The Linux Foundation. All rights reserved.
  */
-
 #include <linux/clk.h>
 #include <linux/slab.h>
 #include <linux/bitops.h>

@@ -3073,10 +3072,6 @@ static int qcom_nandc_probe(struct platform_device *pdev)
 	if (dma_mapping_error(dev, nandc->base_dma))
 		return -ENXIO;
 
-	ret = qcom_nandc_alloc(nandc);
-	if (ret)
-		goto err_nandc_alloc;
-
 	ret = clk_prepare_enable(nandc->core_clk);
 	if (ret)
 		goto err_core_clk;

@@ -3085,6 +3080,10 @@ static int qcom_nandc_probe(struct platform_device *pdev)
 	if (ret)
 		goto err_aon_clk;
 
+	ret = qcom_nandc_alloc(nandc);
+	if (ret)
+		goto err_nandc_alloc;
+
 	ret = qcom_nandc_setup(nandc);
 	if (ret)
 		goto err_setup;

@@ -3096,15 +3095,14 @@ static int qcom_nandc_probe(struct platform_device *pdev)
 	return 0;
 
 err_setup:
+	qcom_nandc_unalloc(nandc);
+err_nandc_alloc:
 	clk_disable_unprepare(nandc->aon_clk);
 err_aon_clk:
 	clk_disable_unprepare(nandc->core_clk);
 err_core_clk:
-	qcom_nandc_unalloc(nandc);
-err_nandc_alloc:
 	dma_unmap_resource(dev, res->start, resource_size(res),
 			   DMA_BIDIRECTIONAL, 0);
-
 	return ret;
 }