Hi Stephen, On Saturday, 29 December 2018 00:30:16 EET Stephen Boyd wrote: > Quoting Marek Vasut (2018-12-16 09:14:29) > > On 12/16/2018 08:19 AM, Laurent Pinchart wrote: > > > 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@xxxxxxxxx> > > >> Cc: Alexey Firago <alexey_firago@xxxxxxxxxx> > > >> Cc: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx> > > >> Cc: Stephen Boyd <sboyd@xxxxxxxxxx> > > >> Cc: linux-renesas-soc@xxxxxxxxxxxxxxx > > >> --- > > >> > > >> 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. > > > > Sure, probe will fail, but it's safer to handle the possibility that > > probe() is broken and this code is reached by properly handling the > > failure instead of doing something obviously wrong (like configuring the > > hardware with value 0). > > I'm fine with this approach. Laurent? So am I. I might add a comment in the vc5_mu_set_parent() function to explain this can't happen. -- Regards, Laurent Pinchart
