[PATCH v2] clk: zynqmp: fix compile testing without ZYNQMP_FIRMWARE

[Arnd Bergmann]

On Mon, Jun 21, 2021 at 3:14 PM Michal Simek <michal.simek at xilinx.com> wrote:
>
> From: Arnd Bergmann <arnd at arndb.de>
>
> When the firmware code is disabled, the incomplete error handling
> in the clk driver causes compile-time warnings:
>
> drivers/clk/zynqmp/pll.c: In function 'zynqmp_pll_recalc_rate':
> drivers/clk/zynqmp/pll.c:147:29: error: 'fbdiv' is used uninitialized [-Werror=uninitialized]
>   147 |         rate =  parent_rate * fbdiv;
>       |                 ~~~~~~~~~~~~^~~~~~~
> In function 'zynqmp_pll_get_mode',
>     inlined from 'zynqmp_pll_recalc_rate' at drivers/clk/zynqmp/pll.c:148:6:
> drivers/clk/zynqmp/pll.c:61:27: error: 'ret_payload' is used uninitialized [-Werror=uninitialized]
>    61 |         return ret_payload[1];
>       |                ~~~~~~~~~~~^~~
> drivers/clk/zynqmp/pll.c: In function 'zynqmp_pll_recalc_rate':
> drivers/clk/zynqmp/pll.c:53:13: note: 'ret_payload' declared here
>    53 |         u32 ret_payload[PAYLOAD_ARG_CNT];
>       |             ^~~~~~~~~~~
> drivers/clk/zynqmp/clk-mux-zynqmp.c: In function 'zynqmp_clk_mux_get_parent':
> drivers/clk/zynqmp/clk-mux-zynqmp.c:57:16: error: 'val' is used uninitialized [-Werror=uninitialized]
>    57 |         return val;
>       |                ^~~
>
> As it was apparently intentional to support this for compile testing
> purposes, change the code to have just enough error handling for the
> compiler to not notice the remaining bugs.
>
> Fixes: 21f237534661 ("clk: zynqmp: Drop dependency on ARCH_ZYNQMP")
> Signed-off-by: Arnd Bergmann <arnd at arndb.de>
> Signed-off-by: Michal Simek <michal.simek at xilinx.com>
> ---
>
> Changes in v2:
> Based on discussion here
> Link: https://lore.kernel.org/r/20210421134844.3297838-1-arnd@kernel.org
> I have updated error return value which I got from clock core based on
> error cases.
>
> zynqmp_clk_mux_get_parent() should return num_parents() as error defined in
> clk_core_get_parent_by_index() where num_parents is incorrect index.
>
> Extend zynqmp_pll_get_mode() with PLL_MODE_ERROR to handle error case.
>
> zynqmp_pll_recalc_rate() returns 0 because __clk_core_init() consider 0 as
> default rate. But maybe -1ul which was used by Arnd is also good option.

Looks good to me. You changed more than I did now, so it might be better
to change my authorship to Co-developed-by, probably not worth respinning
for that.

       Arnd