On 06/07/2017 02:38 PM, Simon Glass wrote:
+Tom for comment
Hi Marek,
On 7 June 2017 at 00:27, Marek Vasut marex@denx.de wrote:
On 06/07/2017 02:16 AM, Simon Glass wrote:
Hi,
On 6 June 2017 at 17:59, Dr. Philipp Tomsich philipp.tomsich@theobroma-systems.com wrote:
Simon,
On 06 Jun 2017, at 23:09, Simon Glass sjg@chromium.org wrote:
Hi Philipp,
On 6 June 2017 at 07:42, Philipp Tomsich philipp.tomsich@theobroma-systems.com wrote:
The regs_otg field in uintptr_t of the platform data structure for dwc2-otg has thus far been an unsigned int, but will eventually be casted into a void*.
This raises the following error with GCC 6.3 and buildman: ../drivers/usb/gadget/dwc2_udc_otg.c: In function 'dwc2_udc_probe': ../drivers/usb/gadget/dwc2_udc_otg.c:821:8: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast] reg = (struct dwc2_usbotg_reg *)pdata->regs_otg; ^
This changes regs_otg to a uintptr_t to ensure that it is large enough to hold any valid pointer (and fix the associated warning).
Signed-off-by: Philipp Tomsich philipp.tomsich@theobroma-systems.com
Changes in v2:
- (new patch) fix a int-to-pointer cast warning for regs_otg in
dwc2-otg to fix a buildman failure for u-boot-rockchip/master@2b19b2f
include/usb/dwc2_udc.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/include/usb/dwc2_udc.h b/include/usb/dwc2_udc.h index 7324d8a..1a370e0 100644 --- a/include/usb/dwc2_udc.h +++ b/include/usb/dwc2_udc.h @@ -16,7 +16,7 @@ struct dwc2_plat_otg_data { int phy_of_node; int (*phy_control)(int on); unsigned int regs_phy;
unsigned int regs_otg;
uintptr_t regs_otg;Can you use ulong instead?
Sure, but can I first ask “why?”. I may reopen an old discussion with this… if so, forgive my ignorance:
uintptr_t makes the most sense for this use case in the C99 (or later) type system, as we want this field to hold an integer (i.e. the address from the physical memory map for one of the register blocks) that will be casted into a pointer. The uintptr_t type will always the matching size in any and all programming models; in contrast, ulong would be wrong for LLP64 (and LLP64 probably “doesn’t matter” in the context of U-Boot anyway).
What I always found odd, was that uintptr_t is optional according to ISO9899. I would thus not have been surprised if there’s a concern for portability between compilers behind this, but then again … U-Boot makes extensive use of GCC extensions (such as inline assembly).
So I am apparently missing something here.
I don't know of any deep reason except that long is defined to be able to hold an address, and ulong makes sense since an address is generally considered unsigned.
U-Boot by convention uses ulong for addresses.
I was under the impression that u-boot by convention uses uintptr_t for addresses.
You can see this all around the code base so I am really just arguing in favour of consistency (and I suppose ulong is easier to type!)
Then I guess half of the codebase is inconsistent.
Actually about 10%:
git grep uintptr_t |wc -l 395 git grep ulong |wc -l 4024
I don't think this is a valid way to count it at all, since uintptr_t is only used for casting pointer to number, while ulong is used for arbitrary numbers.
Clearly we use ulong all over the place for addresses - see image.c, most commands, etc.
But none of those use ulong as device address pointers .
If we are going to change then it should be a deliberate decision and a tree-wide update. I'm happy enough with ulong.
Tom, what do you what to do here?
Regards, Simon