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Date: Tue, 22 Jun 2021 15:12:46 +0800
From: "quanyang.wang" <quanyang.wang@...driver.com>
To: Michal Simek <michal.simek@...inx.com>,
linux-kernel@...r.kernel.org, monstr@...str.eu, git@...inx.com
Cc: Arnd Bergmann <arnd@...db.de>,
Michael Turquette <mturquette@...libre.com>,
Punit Agrawal <punit1.agrawal@...hiba.co.jp>,
Stephen Boyd <sboyd@...nel.org>,
linux-arm-kernel@...ts.infradead.org, linux-clk@...r.kernel.org
Subject: Re: [PATCH v2] clk: zynqmp: fix compile testing without
ZYNQMP_FIRMWARE
Hi Michal & Arnd,
On 6/21/21 9:13 PM, Michal Simek wrote:
> From: Arnd Bergmann <arnd@...db.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@...db.de>
> Signed-off-by: Michal Simek <michal.simek@...inx.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;
Thanks,
Quanyang
> rate = parent_rate * fbdiv;
> if (zynqmp_pll_get_mode(hw) == PLL_MODE_FRAC) {
>
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