* [PATCH] clk: imx8qxp-lpcg: Warn against devm_platform_ioremap_resource
@ 2019-12-09 20:56 Leonard Crestez
2019-12-10 6:07 ` Peng Fan
2019-12-11 8:06 ` Shawn Guo
0 siblings, 2 replies; 3+ messages in thread
From: Leonard Crestez @ 2019-12-09 20:56 UTC (permalink / raw)
To: Stephen Boyd, Shawn Guo, Dong Aisheng
Cc: Peng Fan, Michael Turquette, Yangtao Li, Anson Huang,
Fabio Estevam, Rob Herring, Mark Rutland, linux-clk, kernel,
linux-imx
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>
---
drivers/clk/imx/clk-imx8qxp-lpcg.c | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/drivers/clk/imx/clk-imx8qxp-lpcg.c b/drivers/clk/imx/clk-imx8qxp-lpcg.c
index c0aff7ca6374..04c8ee35e14c 100644
--- a/drivers/clk/imx/clk-imx8qxp-lpcg.c
+++ b/drivers/clk/imx/clk-imx8qxp-lpcg.c
@@ -171,10 +171,21 @@ static int imx8qxp_lpcg_clk_probe(struct platform_device *pdev)
ss_lpcg = of_device_get_match_data(dev);
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;
base = devm_ioremap(dev, res->start, resource_size(res));
if (!base)
--
2.17.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* RE: [PATCH] clk: imx8qxp-lpcg: Warn against devm_platform_ioremap_resource
2019-12-09 20:56 [PATCH] clk: imx8qxp-lpcg: Warn against devm_platform_ioremap_resource Leonard Crestez
@ 2019-12-10 6:07 ` Peng Fan
2019-12-11 8:06 ` Shawn Guo
1 sibling, 0 replies; 3+ messages in thread
From: Peng Fan @ 2019-12-10 6:07 UTC (permalink / raw)
To: Leonard Crestez, Stephen Boyd, Shawn Guo, Aisheng Dong
Cc: Michael Turquette, Yangtao Li, Anson Huang, Fabio Estevam,
Rob Herring, Mark Rutland, linux-clk@vger.kernel.org,
kernel@pengutronix.de, dl-linux-imx
> Subject: [PATCH] clk: imx8qxp-lpcg: Warn against
> devm_platform_ioremap_resource
>
> 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>
> ---
> drivers/clk/imx/clk-imx8qxp-lpcg.c | 11 +++++++++++
> 1 file changed, 11 insertions(+)
>
> diff --git a/drivers/clk/imx/clk-imx8qxp-lpcg.c
> b/drivers/clk/imx/clk-imx8qxp-lpcg.c
> index c0aff7ca6374..04c8ee35e14c 100644
> --- a/drivers/clk/imx/clk-imx8qxp-lpcg.c
> +++ b/drivers/clk/imx/clk-imx8qxp-lpcg.c
> @@ -171,10 +171,21 @@ static int imx8qxp_lpcg_clk_probe(struct
> platform_device *pdev)
>
> ss_lpcg = of_device_get_match_data(dev);
> 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;
> base = devm_ioremap(dev, res->start, resource_size(res));
> if (!base)
> --
> 2.17.1
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] clk: imx8qxp-lpcg: Warn against devm_platform_ioremap_resource
2019-12-09 20:56 [PATCH] clk: imx8qxp-lpcg: Warn against devm_platform_ioremap_resource Leonard Crestez
2019-12-10 6:07 ` Peng Fan
@ 2019-12-11 8:06 ` Shawn Guo
1 sibling, 0 replies; 3+ messages in thread
From: Shawn Guo @ 2019-12-11 8:06 UTC (permalink / raw)
To: Leonard Crestez
Cc: Stephen Boyd, Dong Aisheng, Peng Fan, Michael Turquette,
Yangtao Li, Anson Huang, Fabio Estevam, Rob Herring, Mark Rutland,
linux-clk, kernel, linux-imx
On Mon, Dec 09, 2019 at 10:56:28PM +0200, Leonard Crestez wrote:
> 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>
Applied, thanks.
^ permalink raw reply [flat|nested] 3+ messages in thread
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2019-12-09 20:56 [PATCH] clk: imx8qxp-lpcg: Warn against devm_platform_ioremap_resource Leonard Crestez
2019-12-10 6:07 ` Peng Fan
2019-12-11 8:06 ` Shawn Guo
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