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SubjectRe: [PATCH] devres: keep both device name and resource name in pretty name
On Sat, 30 May 2020 at 23:06, Vladimir Oltean <olteanv@gmail.com> wrote:
>
> From: Vladimir Oltean <vladimir.oltean@nxp.com>
>
> Some device drivers have many memory regions, and sometimes debugging is
> easiest using devmem on its register map. Take for example a networking
> switch. Its memory map used to look like this in /proc/iomem:
>
> 1fc000000-1fc3fffff : pcie@1f0000000
> 1fc000000-1fc3fffff : 0000:00:00.5
> 1fc010000-1fc01ffff : sys
> 1fc030000-1fc03ffff : rew
> 1fc060000-1fc0603ff : s2
> 1fc070000-1fc0701ff : devcpu_gcb
> 1fc080000-1fc0800ff : qs
> 1fc090000-1fc0900cb : ptp
> 1fc100000-1fc10ffff : port0
> 1fc110000-1fc11ffff : port1
> 1fc120000-1fc12ffff : port2
> 1fc130000-1fc13ffff : port3
> 1fc140000-1fc14ffff : port4
> 1fc150000-1fc15ffff : port5
> 1fc200000-1fc21ffff : qsys
> 1fc280000-1fc28ffff : ana
>
> But after said patch, the information is now presented in a much more
> opaque way:
>
> 1fc000000-1fc3fffff : pcie@1f0000000
> 1fc000000-1fc3fffff : 0000:00:00.5
> 1fc010000-1fc01ffff : 0000:00:00.5
> 1fc030000-1fc03ffff : 0000:00:00.5
> 1fc060000-1fc0603ff : 0000:00:00.5
> 1fc070000-1fc0701ff : 0000:00:00.5
> 1fc080000-1fc0800ff : 0000:00:00.5
> 1fc090000-1fc0900cb : 0000:00:00.5
> 1fc100000-1fc10ffff : 0000:00:00.5
> 1fc110000-1fc11ffff : 0000:00:00.5
> 1fc120000-1fc12ffff : 0000:00:00.5
> 1fc130000-1fc13ffff : 0000:00:00.5
> 1fc140000-1fc14ffff : 0000:00:00.5
> 1fc150000-1fc15ffff : 0000:00:00.5
> 1fc200000-1fc21ffff : 0000:00:00.5
> 1fc280000-1fc28ffff : 0000:00:00.5
>
> It is a fair comment that /proc/iomem might be confusing when it shows
> resources without an associated device, but we can do better than just
> hide the resource name altogether. Namely, we can print the device
> name _and_ the resource name. Like this:
>
> 1fc000000-1fc3fffff : pcie@1f0000000
> 1fc000000-1fc3fffff : 0000:00:00.5
> 1fc010000-1fc01ffff : 0000:00:00.5 sys
> 1fc030000-1fc03ffff : 0000:00:00.5 rew
> 1fc060000-1fc0603ff : 0000:00:00.5 s2
> 1fc070000-1fc0701ff : 0000:00:00.5 devcpu_gcb
> 1fc080000-1fc0800ff : 0000:00:00.5 qs
> 1fc090000-1fc0900cb : 0000:00:00.5 ptp
> 1fc100000-1fc10ffff : 0000:00:00.5 port0
> 1fc110000-1fc11ffff : 0000:00:00.5 port1
> 1fc120000-1fc12ffff : 0000:00:00.5 port2
> 1fc130000-1fc13ffff : 0000:00:00.5 port3
> 1fc140000-1fc14ffff : 0000:00:00.5 port4
> 1fc150000-1fc15ffff : 0000:00:00.5 port5
> 1fc200000-1fc21ffff : 0000:00:00.5 qsys
> 1fc280000-1fc28ffff : 0000:00:00.5 ana
>
> Fixes: 8d84b18f5678 ("devres: always use dev_name() in devm_ioremap_resource()")
> Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
> ---

I just realized I haven't done any error checking whatsoever on memory
allocation. So let's keep discussing only on the general idea of the
patch, if people are ok with it, I'll send a v2.

> lib/devres.c | 12 +++++++++++-
> 1 file changed, 11 insertions(+), 1 deletion(-)
>
> diff --git a/lib/devres.c b/lib/devres.c
> index 6ef51f159c54..25b78b0cb5cc 100644
> --- a/lib/devres.c
> +++ b/lib/devres.c
> @@ -119,6 +119,7 @@ __devm_ioremap_resource(struct device *dev, const struct resource *res,
> {
> resource_size_t size;
> void __iomem *dest_ptr;
> + char *pretty_name;
>
> BUG_ON(!dev);
>
> @@ -129,7 +130,16 @@ __devm_ioremap_resource(struct device *dev, const struct resource *res,
>
> size = resource_size(res);
>
> - if (!devm_request_mem_region(dev, res->start, size, dev_name(dev))) {
> + if (res->name) {
> + int len = strlen(dev_name(dev)) + strlen(res->name) + 2;
> +
> + pretty_name = devm_kzalloc(dev, len, GFP_KERNEL);
> + sprintf(pretty_name, "%s %s", dev_name(dev), res->name);
> + } else {
> + pretty_name = devm_kstrdup(dev, dev_name(dev), GFP_KERNEL);
> + }
> +
> + if (!devm_request_mem_region(dev, res->start, size, pretty_name)) {
> dev_err(dev, "can't request region for resource %pR\n", res);
> return IOMEM_ERR_PTR(-EBUSY);
> }
> --
> 2.25.1
>

Thanks,
-Vladimir

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