Hi Paul,
On Thu, 4 Jun 2015 23:02:25 +0000 (UTC) Paul Walmsley paul@pwsan.com wrote:
Hi folks
just a brief comment on this one:
On Thu, 30 Apr 2015, Boris Brezillon wrote:
Clock rates are stored in an unsigned long field, but ->round_rate() (which returns a rounded rate from a requested one) returns a long value (errors are reported using negative error codes), which can lead to long overflow if the clock rate exceed 2Ghz.
Change ->round_rate() prototype to return 0 or an error code, and pass the requested rate as a pointer so that it can be adjusted depending on hardware capabilities.
...
diff --git a/Documentation/clk.txt b/Documentation/clk.txt index 0e4f90a..fca8b7a 100644 --- a/Documentation/clk.txt +++ b/Documentation/clk.txt @@ -68,8 +68,8 @@ the operations defined in clk.h: int (*is_enabled)(struct clk_hw *hw); unsigned long (*recalc_rate)(struct clk_hw *hw, unsigned long parent_rate);
long (*round_rate)(struct clk_hw *hw,unsigned long rate,
int (*round_rate)(struct clk_hw *hw,unsigned long *rate, unsigned long *parent_rate);I'd suggest that we should probably go straight to 64-bit rates. There are already plenty of clock sources that can generate rates higher than 4GiHz.
Yep, that was something I was considering too. If Stephen agrees I'll change that in the next version. BTW, you're referring to the second version of this patch, but things have changed a bit: Stephen recommended to only modify the ->determine_rate() prototype and pass a structure instead of a list of arguments. Here is the last version of this series [1].
Best Regards,
Boris
[1]http://patchwork.linux-mips.org/patch/10092/