Quoting Marek Vasut (2018-12-16 09:14:29) > On 12/16/2018 08:19 AM, Laurent Pinchart wrote: > > 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@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?
