linux-kernel - [PATCH] devres: always use dev_name() in devm_ioremap

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Message-ID: <1c848f62-e1d1-514f-f097-722d60f56711@cogentembedded.com>
Date:   Tue, 29 Jan 2019 13:56:19 +0300
From:   Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
To:     linux-kernel@...r.kernel.org
Cc:     gregkh@...uxfoundation.org
Subject: [PATCH] devres: always use dev_name() in devm_ioremap_resource()

devm_ioremap_resource() prefers calling devm_request_mem_region() with a
resource name instead of a device name -- this looks pretty iff a resource
name isn't specified via a device tree with a "reg-names" property (in this
case, a resource name is set to a device node's full name), but if it is,
it doesn't really scale since these names are only unique to a given device
node, not globally; so, looking at the output of 'cat /proc/iomem', you do
not have an idea which memory region belongs to which device (see "dirmap",
"regs", and "wbuf" lines below):

08000000-0bffffff : dirmap
48000000-bfffffff : System RAM
  48000000-48007fff : reserved
  48080000-48b0ffff : Kernel code
  48b10000-48b8ffff : reserved
  48b90000-48c7afff : Kernel data
  bc6a4000-bcbfffff : reserved
  bcc0f000-bebfffff : reserved
  bec0e000-bec0efff : reserved
  bec11000-bec11fff : reserved
  bec12000-bec14fff : reserved
  bec15000-bfffffff : reserved
e6050000-e605004f : gpio@...50000
e6051000-e605104f : gpio@...51000
e6052000-e605204f : gpio@...52000
e6053000-e605304f : gpio@...53000
e6054000-e605404f : gpio@...54000
e6055000-e605504f : gpio@...55000
e6060000-e606050b : pin-controller@...60000
e6e60000-e6e6003f : e6e60000.serial
e7400000-e7400fff : ethernet@...00000
ee200000-ee2001ff : regs
ee208000-ee2080ff : wbuf

I think that devm_request_mem_region() should be called with dev_name()
despite the region names won't look as pretty as before (however, we gain
more consistency with e.g. the serial driver:

08000000-0bffffff : ee200000.rpc
48000000-bfffffff : System RAM
  48000000-48007fff : reserved
  48080000-48b0ffff : Kernel code
  48b10000-48b8ffff : reserved
  48b90000-48c7afff : Kernel data
  bc6a4000-bcbfffff : reserved
  bcc0f000-bebfffff : reserved
  bec0e000-bec0efff : reserved
  bec11000-bec11fff : reserved
  bec12000-bec14fff : reserved
  bec15000-bfffffff : reserved
e6050000-e605004f : e6050000.gpio
e6051000-e605104f : e6051000.gpio
e6052000-e605204f : e6052000.gpio
e6053000-e605304f : e6053000.gpio
e6054000-e605404f : e6054000.gpio
e6055000-e605504f : e6055000.gpio
e6060000-e606050b : e6060000.pin-controller
e6e60000-e6e6003f : e6e60000.serial
e7400000-e7400fff : e7400000.ethernet
ee200000-ee2001ff : ee200000.rpc
ee208000-ee2080ff : ee200000.rpc

Fixes: 72f8c0bfa0de ("lib: devres: add convenience function to remap a resource")
Signed-off-by: Sergei Shtylyov <sergei.shtylyov@...entembedded.com>

---
The patch is against the 'driver-core-linus' branch of Greg KH's 'driver-core'
repo (for the lack of a better base).

 lib/devres.c |    4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

Index: driver-core/lib/devres.c
===================================================================
--- driver-core.orig/lib/devres.c
+++ driver-core/lib/devres.c
@@ -134,7 +134,6 @@ EXPORT_SYMBOL(devm_iounmap);
 void __iomem *devm_ioremap_resource(struct device *dev, struct resource *res)
 {
 	resource_size_t size;
-	const char *name;
 	void __iomem *dest_ptr;
 
 	BUG_ON(!dev);
@@ -145,9 +144,8 @@ void __iomem *devm_ioremap_resource(stru
 	}
 
 	size = resource_size(res);
-	name = res->name ?: dev_name(dev);
 
-	if (!devm_request_mem_region(dev, res->start, size, name)) {
+	if (!devm_request_mem_region(dev, res->start, size, dev_name(dev))) {
 		dev_err(dev, "can't request region for resource %pR\n", res);
 		return IOMEM_ERR_PTR(-EBUSY);
 	}