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

[Michal Simek]

Hi,

On 6/22/21 9:12 AM, quanyang.wang wrote:
> Hi Michal & Arnd,
> 
> On 6/21/21 9:13 PM, Michal Simek 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.
>>
>> ---
>>   drivers/clk/zynqmp/clk-mux-zynqmp.c | 10 ++++++++--
>>   drivers/clk/zynqmp/pll.c            | 15 ++++++++++-----
>>   2 files changed, 18 insertions(+), 7 deletions(-)
>>
>> diff --git a/drivers/clk/zynqmp/clk-mux-zynqmp.c
>> b/drivers/clk/zynqmp/clk-mux-zynqmp.c
>> index 06194149be83..d576c900dee0 100644
>> --- a/drivers/clk/zynqmp/clk-mux-zynqmp.c
>> +++ b/drivers/clk/zynqmp/clk-mux-zynqmp.c
>> @@ -38,7 +38,7 @@ struct zynqmp_clk_mux {
>>    * zynqmp_clk_mux_get_parent() - Get parent of clock
>>    * @hw:        handle between common and hardware-specific interfaces
>>    *
>> - * Return: Parent index
>> + * Return: Parent index on success or number of parents in case of error
>>    */
>>   static u8 zynqmp_clk_mux_get_parent(struct clk_hw *hw)
>>   {
>> @@ -50,9 +50,15 @@ static u8 zynqmp_clk_mux_get_parent(struct clk_hw *hw)
>>         ret = zynqmp_pm_clock_getparent(clk_id, &val);
>>   -    if (ret)
>> +    if (ret) {
>>           pr_warn_once("%s() getparent failed for clock: %s, ret = %d\n",
>>                    __func__, clk_name, ret);
>> +        /*
>> +         * clk_core_get_parent_by_index() takes num_parents as incorrect
>> +         * index which is exactly what I want to return here
>> +         */
>> +        return clk_hw_get_num_parents(hw);
>> +    }
>>         return val;
>>   }
>> diff --git a/drivers/clk/zynqmp/pll.c b/drivers/clk/zynqmp/pll.c
>> index abe6afbf3407..3fe4d21227d0 100644
>> --- a/drivers/clk/zynqmp/pll.c
>> +++ b/drivers/clk/zynqmp/pll.c
>> @@ -31,8 +31,9 @@ struct zynqmp_pll {
>>   #define PS_PLL_VCO_MAX 3000000000UL
>>     enum pll_mode {
>> -    PLL_MODE_INT,
>> -    PLL_MODE_FRAC,
>> +    PLL_MODE_INT = 0,
>> +    PLL_MODE_FRAC = 1,
>> +    PLL_MODE_ERROR = 2,
>>   };
>>     #define FRAC_OFFSET 0x8
>> @@ -54,9 +55,11 @@ static inline enum pll_mode
>> zynqmp_pll_get_mode(struct clk_hw *hw)
>>       int ret;
>>         ret = zynqmp_pm_get_pll_frac_mode(clk_id, ret_payload);
>> -    if (ret)
>> +    if (ret) {
>>           pr_warn_once("%s() PLL get frac mode failed for %s, ret =
>> %d\n",
>>                    __func__, clk_name, ret);
>> +        return PLL_MODE_ERROR;
>> +    }
>>         return ret_payload[1];
>>   }
>> @@ -126,7 +129,7 @@ static long zynqmp_pll_round_rate(struct clk_hw
>> *hw, unsigned long rate,
>>    * @hw:            Handle between common and hardware-specific
>> interfaces
>>    * @parent_rate:    Clock frequency of parent clock
>>    *
>> - * Return: Current clock frequency
>> + * Return: Current clock frequency or 0 in case of error
>>    */
>>   static unsigned long zynqmp_pll_recalc_rate(struct clk_hw *hw,
>>                           unsigned long parent_rate)
>> @@ -140,9 +143,11 @@ static unsigned long
>> zynqmp_pll_recalc_rate(struct clk_hw *hw,
>>       int ret;
>>         ret = zynqmp_pm_clock_getdivider(clk_id, &fbdiv);
>> -    if (ret)
>> +    if (ret) {
>>           pr_warn_once("%s() get divider failed for %s, ret = %d\n",
>>                    __func__, clk_name, ret);
>> +        return 0ul;
>> +    }
>>   
> Since zynqmp_pll_get_mode may return err now, maybe here should add a
> condition check for PLL_MODE_ERR:
>     if (zynqmp_pll_get_mode(hw) == PLL_MODE_ERR)
>         return 0ul;

Agree. I have sent v3 with this there. Please review.

Thanks,
Michal