Re: [PATCH] clk: vc5: Abort clock configuration without upstream clock

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Marek,

Thank you for the patch.

On Saturday, 15 December 2018 02:55:19 EET Marek Vasut wrote:
> In case the upstream clock are not set, which can happen in case the
> VC5 has no valid upstream clock, the $src variable is used uninited
> by regmap_update_bits(). Check for this condition and return -EINVAL
> in such case.

Note that the probe() function will fail in this case, so vc5_mux_set_parent() 
won't be reached.

> Note that in case the VC5 has no valid upstream clock, the VC5 can
> not operate correctly. That is a hardware property of the VC5. The
> internal oscilator present in some VC5 models is also considered
> upstream clock.
> 
> Signed-off-by: Marek Vasut <marek.vasut+renesas@gmail.com>
> Cc: Alexey Firago <alexey_firago@mentor.com>
> Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> Cc: Stephen Boyd <sboyd@kernel.org>
> Cc: linux-renesas-soc@vger.kernel.org
> ---
> NOTE: This is an updated version of:
>       https://patchwork.kernel.org/patch/10731699/
> ---
>  drivers/clk/clk-versaclock5.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/clk/clk-versaclock5.c b/drivers/clk/clk-versaclock5.c
> index 5b393e711e94..b10801506518 100644
> --- a/drivers/clk/clk-versaclock5.c
> +++ b/drivers/clk/clk-versaclock5.c
> @@ -262,8 +262,10 @@ static int vc5_mux_set_parent(struct clk_hw *hw, u8
> index)
> 
>  		if (vc5->clk_mux_ins == VC5_MUX_IN_XIN)
>  			src = VC5_PRIM_SRC_SHDN_EN_XTAL;
> -		if (vc5->clk_mux_ins == VC5_MUX_IN_CLKIN)
> +		else if (vc5->clk_mux_ins == VC5_MUX_IN_CLKIN)
>  			src = VC5_PRIM_SRC_SHDN_EN_CLKIN;
> +		else
> +			return -EINVAL;
>  	}

I'd rather go for Stephen's approach if the goal is just to silence a warning 
for a condition that can't happen in practice.

>  	return regmap_update_bits(vc5->regmap, VC5_PRIM_SRC_SHDN, mask, src);

-- 
Regards,

Laurent Pinchart