On 09/06/2017 06:03 PM, Masahiro Yamada wrote:
Hi David,
2017-09-07 2:36 GMT+09:00 David Daney <ddaney@xxxxxxxxxxxxxxxxxx>:
On 09/05/2017 09:20 PM, Masahiro Yamada wrote:
Hi David,
2017-09-06 11:09 GMT+09:00 David Daney <ddaney@xxxxxxxxxxxxxxxxxx>:
On 09/05/2017 06:40 PM, Masahiro Yamada wrote:
IRQ_DOMAIN_HIERARCHY is not user-configurable, but supposed to be
selected by drivers that need IRQ domain hierarchy support.
GPIO_THUNDERX is the only user of "depends on IRQ_DOMAIN_HIERARCHY".
This means, we can not enable GPIO_THUNDERX unless other drivers
select IRQ_DOMAIN_HIERARCHY elsewhere. This is odd. Flip the logic.
Signed-off-by: Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx>
IRQ_DOMAIN_HIERARCHY is set as a result of ARCH_THUNDER (this SoC
hardware),
so it actually works as-is.
Right, ARCH_THUNDER does not select it directly,
but does it indirectly. (this is not so clear...)
ARCH_THUNDER -> ARM64 -> ARM_GIC -> IRQ_DOMAIN_HIERARCHY
That said, this looks like a reasonable
improvement, and will allow the COMPILE_TEST to enable it, so...
Acked-by: David Daney <david.daney@xxxxxxxxxx>
BTW, I could not understand your intention of
(64BIT && COMPILE_TEST)
The driver uses readq()/writeq(), which are not available in some 32BIT
kernels. So to ensure that it can build without error we depend on 64BIT as
a proxy for the availability of readq()/writeq()
IMHO, drivers code should not depend on CPU architecture too much.
The CPU and the device are in a SoC (both on the same silicon die),
there is no way they can be used apart from one another.
Does the following make sense for your driver?
- split {read,write}q into two transactions of {read,write}l
No. The registers must be accessed with 64-bit operations.
We are not going to screw around complicating the driver so that it can
work on hypothetical non-existent systems.
If we ever put this GPIO hardware unit in a system with a 32-bit CPU, we
will at that time, and only then, modify it to work with 32-bit operations.
or
- include <linux/io-64-nonatomic-hi-lo.h> or
<linux-io-64-nonatomic-lo-hi.h>
(choose a suitable one for your driver)
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