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clk: imx8qxp-lpcg: Warn against devm_platform_ioremap_resource

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On imx8 the LPCG nodes map entire subsystems and overlap peripherals,
this means that using devm_platform_ioremap_resource will cause many
devices to fail to probe including serial ports.

Well-meaning but boot-breaking patches were posted multiple times so add
a comment explaining this issue.

Suggested-by: Peng Fan <peng.fan@nxp.com>
Signed-off-by: Leonard Crestez <leonard.crestez@nxp.com>
Reviewed-by: Peng Fan <peng.fan@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
This commit is contained in:
Leonard Crestez 2019-12-09 22:56:28 +02:00 committed by Shawn Guo
parent 134d43bb1f
commit 249fce6f3a
1 changed files with 11 additions and 0 deletions
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11
drivers/clk/imx/clk-imx8qxp-lpcg.c
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@ -173,6 +173,17 @@ static int imx8qxp_lpcg_clk_probe(struct platform_device *pdev)
if (!ss_lpcg)
return -ENODEV;
/*
* Please don't replace this with devm_platform_ioremap_resource.
*
* devm_platform_ioremap_resource calls devm_ioremap_resource which
* differs from devm_ioremap by also calling devm_request_mem_region
* and preventing other mappings in the same area.
*
* On imx8 the LPCG nodes map entire subsystems and overlap
* peripherals, this means that using devm_platform_ioremap_resource
* will cause many devices to fail to probe including serial ports.
*/
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
if (!res)
return -EINVAL;