| Message ID | 20240929-fix_glitch_free-v1-2-22f9c36b7edf@amlogic.com (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Neil Armstrong |
| Headers | show |
| Series | clk: Fix issues related to CLK_IGNORE_UNUSED failures and amlogic glitch free mux | expand |
On Sun 29 Sep 2024 at 14:10, Chuan Liu via B4 Relay <devnull+chuan.liu.amlogic.com@kernel.org> wrote: > From: Chuan Liu <chuan.liu@amlogic.com> > > glitch free mux has two clock channels (channel 0 and channel 1) with > the same configuration. When the frequency needs to be changed, the two > channels ping-pong to ensure clock continuity and suppress glitch. > > Channel 0 of glitch free mux is not only the clock source for the mux, > but also the working clock for glitch free mux. Therefore, when glitch > free mux switches, it is necessary to ensure that channel 0 has a clock > input, otherwise glitch free mux will not work and cannot switch to the > target channel. > > Add flag CLK_SET_RATE_GATE to channels 0 and 1 to implement Ping-Pong > switchover to suppress glitch. > > glitch free mux Add flag CLK_OPS_PARENT_ENABLE to ensure that channel 0 > has clock input when switching channels. Several 'glitch_free' are not touched by your change. Why ? I thinking about the mali glitch free mux for example. > > Change-Id: I6fa6ff92f7b2e0a13dd7a27feb0e8568be3ca9f9 > Signed-off-by: Chuan Liu <chuan.liu@amlogic.com> > --- > drivers/clk/meson/a1-peripherals.c | 12 ++++++------ > drivers/clk/meson/axg.c | 16 ++++++++++------ > drivers/clk/meson/c3-peripherals.c | 6 +++--- > drivers/clk/meson/g12a.c | 18 +++++++++++------- > drivers/clk/meson/gxbb.c | 18 +++++++++++------- > drivers/clk/meson/s4-peripherals.c | 32 ++++++++++++++++---------------- > 6 files changed, 57 insertions(+), 45 deletions(-) > > diff --git a/drivers/clk/meson/a1-peripherals.c b/drivers/clk/meson/a1-peripherals.c > index 7aa6abb2eb1f..7f515e002adb 100644 > --- a/drivers/clk/meson/a1-peripherals.c > +++ b/drivers/clk/meson/a1-peripherals.c > @@ -423,7 +423,7 @@ static struct clk_regmap dspa_a = { > &dspa_a_div.hw > }, > .num_parents = 1, > - .flags = CLK_SET_RATE_PARENT, > + .flags = CLK_SET_RATE_PARENT | CLK_SET_RATE_GATE, > }, > }; > > @@ -471,7 +471,7 @@ static struct clk_regmap dspa_b = { > &dspa_b_div.hw > }, > .num_parents = 1, > - .flags = CLK_SET_RATE_PARENT, > + .flags = CLK_SET_RATE_PARENT | CLK_SET_RATE_GATE, > }, > }; > > @@ -489,7 +489,7 @@ static struct clk_regmap dspa_sel = { > &dspa_b.hw, > }, > .num_parents = 2, > - .flags = CLK_SET_RATE_PARENT, > + .flags = CLK_SET_RATE_PARENT | CLK_OPS_PARENT_ENABLE, > }, > }; > > @@ -569,7 +569,7 @@ static struct clk_regmap dspb_a = { > &dspb_a_div.hw > }, > .num_parents = 1, > - .flags = CLK_SET_RATE_PARENT, > + .flags = CLK_SET_RATE_PARENT | CLK_SET_RATE_GATE, > }, > }; > > @@ -617,7 +617,7 @@ static struct clk_regmap dspb_b = { > &dspb_b_div.hw > }, > .num_parents = 1, > - .flags = CLK_SET_RATE_PARENT, > + .flags = CLK_SET_RATE_PARENT | CLK_SET_RATE_GATE, > }, > }; > > @@ -635,7 +635,7 @@ static struct clk_regmap dspb_sel = { > &dspb_b.hw, > }, > .num_parents = 2, > - .flags = CLK_SET_RATE_PARENT, > + .flags = CLK_SET_RATE_PARENT | CLK_OPS_PARENT_ENABLE, > }, > }; > > diff --git a/drivers/clk/meson/axg.c b/drivers/clk/meson/axg.c > index 1b08daf579b2..e2d3266f4b45 100644 > --- a/drivers/clk/meson/axg.c > +++ b/drivers/clk/meson/axg.c > @@ -1077,7 +1077,8 @@ static struct clk_regmap axg_vpu_0 = { > * We want to avoid CCF to disable the VPU clock if > * display has been set by Bootloader > */ > - .flags = CLK_SET_RATE_PARENT | CLK_IGNORE_UNUSED, > + .flags = CLK_SET_RATE_PARENT | CLK_IGNORE_UNUSED | > + CLK_SET_RATE_GATE, > }, > }; > > @@ -1126,7 +1127,8 @@ static struct clk_regmap axg_vpu_1 = { > * We want to avoid CCF to disable the VPU clock if > * display has been set by Bootloader > */ > - .flags = CLK_SET_RATE_PARENT | CLK_IGNORE_UNUSED, > + .flags = CLK_SET_RATE_PARENT | CLK_IGNORE_UNUSED | > + CLK_SET_RATE_GATE, > }, > }; > > @@ -1144,7 +1146,7 @@ static struct clk_regmap axg_vpu = { > &axg_vpu_1.hw > }, > .num_parents = 2, > - .flags = CLK_SET_RATE_NO_REPARENT, > + .flags = CLK_SET_RATE_NO_REPARENT | CLK_OPS_PARENT_ENABLE, > }, > }; > > @@ -1194,7 +1196,8 @@ static struct clk_regmap axg_vapb_0 = { > &axg_vapb_0_div.hw > }, > .num_parents = 1, > - .flags = CLK_SET_RATE_PARENT | CLK_IGNORE_UNUSED, > + .flags = CLK_SET_RATE_PARENT | CLK_IGNORE_UNUSED | > + CLK_SET_RATE_GATE, > }, > }; > > @@ -1242,7 +1245,8 @@ static struct clk_regmap axg_vapb_1 = { > &axg_vapb_1_div.hw > }, > .num_parents = 1, > - .flags = CLK_SET_RATE_PARENT | CLK_IGNORE_UNUSED, > + .flags = CLK_SET_RATE_PARENT | CLK_IGNORE_UNUSED | > + CLK_SET_RATE_GATE, > }, > }; > > @@ -1260,7 +1264,7 @@ static struct clk_regmap axg_vapb_sel = { > &axg_vapb_1.hw > }, > .num_parents = 2, > - .flags = CLK_SET_RATE_NO_REPARENT, > + .flags = CLK_SET_RATE_NO_REPARENT | CLK_OPS_PARENT_ENABLE, > }, > }; > > diff --git a/drivers/clk/meson/c3-peripherals.c b/drivers/clk/meson/c3-peripherals.c > index 7dcbf4ebee07..27343a73a521 100644 > --- a/drivers/clk/meson/c3-peripherals.c > +++ b/drivers/clk/meson/c3-peripherals.c > @@ -1364,7 +1364,7 @@ static struct clk_regmap hcodec_0 = { > &hcodec_0_div.hw > }, > .num_parents = 1, > - .flags = CLK_SET_RATE_PARENT, > + .flags = CLK_SET_RATE_PARENT | CLK_SET_RATE_GATE, > }, > }; > > @@ -1411,7 +1411,7 @@ static struct clk_regmap hcodec_1 = { > &hcodec_1_div.hw > }, > .num_parents = 1, > - .flags = CLK_SET_RATE_PARENT, > + .flags = CLK_SET_RATE_PARENT | CLK_SET_RATE_GATE, > }, > }; > > @@ -1431,7 +1431,7 @@ static struct clk_regmap hcodec = { > .ops = &clk_regmap_mux_ops, > .parent_data = hcodec_parent_data, > .num_parents = ARRAY_SIZE(hcodec_parent_data), > - .flags = CLK_SET_RATE_PARENT, > + .flags = CLK_SET_RATE_PARENT | CLK_OPS_PARENT_ENABLE, > }, > }; > > diff --git a/drivers/clk/meson/g12a.c b/drivers/clk/meson/g12a.c > index d3539fe9f7af..21a25001e904 100644 > --- a/drivers/clk/meson/g12a.c > +++ b/drivers/clk/meson/g12a.c > @@ -2746,7 +2746,8 @@ static struct clk_regmap g12a_vpu_0 = { > .ops = &clk_regmap_gate_ops, > .parent_hws = (const struct clk_hw *[]) { &g12a_vpu_0_div.hw }, > .num_parents = 1, > - .flags = CLK_SET_RATE_PARENT | CLK_IGNORE_UNUSED, > + .flags = CLK_SET_RATE_PARENT | CLK_IGNORE_UNUSED | > + CLK_SET_RATE_GATE, > }, > }; > > @@ -2790,7 +2791,8 @@ static struct clk_regmap g12a_vpu_1 = { > .ops = &clk_regmap_gate_ops, > .parent_hws = (const struct clk_hw *[]) { &g12a_vpu_1_div.hw }, > .num_parents = 1, > - .flags = CLK_SET_RATE_PARENT | CLK_IGNORE_UNUSED, > + .flags = CLK_SET_RATE_PARENT | CLK_IGNORE_UNUSED | > + CLK_SET_RATE_GATE, > }, > }; > > @@ -2812,7 +2814,7 @@ static struct clk_regmap g12a_vpu = { > &g12a_vpu_1.hw, > }, > .num_parents = 2, > - .flags = CLK_SET_RATE_NO_REPARENT, > + .flags = CLK_SET_RATE_NO_REPARENT | CLK_OPS_PARENT_ENABLE, > }, > }; > > @@ -3035,7 +3037,8 @@ static struct clk_regmap g12a_vapb_0 = { > &g12a_vapb_0_div.hw > }, > .num_parents = 1, > - .flags = CLK_SET_RATE_PARENT | CLK_IGNORE_UNUSED, > + .flags = CLK_SET_RATE_PARENT | CLK_IGNORE_UNUSED | > + CLK_SET_RATE_GATE, > }, > }; > > @@ -3083,7 +3086,8 @@ static struct clk_regmap g12a_vapb_1 = { > &g12a_vapb_1_div.hw > }, > .num_parents = 1, > - .flags = CLK_SET_RATE_PARENT | CLK_IGNORE_UNUSED, > + .flags = CLK_SET_RATE_PARENT | CLK_IGNORE_UNUSED | > + CLK_SET_RATE_GATE, > }, > }; > > @@ -3105,7 +3109,7 @@ static struct clk_regmap g12a_vapb_sel = { > &g12a_vapb_1.hw, > }, > .num_parents = 2, > - .flags = CLK_SET_RATE_NO_REPARENT, > + .flags = CLK_SET_RATE_NO_REPARENT | CLK_OPS_PARENT_ENABLE, > }, > }; > > @@ -4039,7 +4043,7 @@ static struct clk_regmap g12a_mali = { > .ops = &clk_regmap_mux_ops, > .parent_hws = g12a_mali_parent_hws, > .num_parents = 2, > - .flags = CLK_SET_RATE_PARENT, > + .flags = CLK_SET_RATE_PARENT | CLK_OPS_PARENT_ENABLE, > }, > }; > > diff --git a/drivers/clk/meson/gxbb.c b/drivers/clk/meson/gxbb.c > index 262c318edbd5..812b3e20c366 100644 > --- a/drivers/clk/meson/gxbb.c > +++ b/drivers/clk/meson/gxbb.c > @@ -1132,7 +1132,7 @@ static struct clk_regmap gxbb_mali = { > .ops = &clk_regmap_mux_ops, > .parent_hws = gxbb_mali_parent_hws, > .num_parents = 2, > - .flags = CLK_SET_RATE_PARENT, > + .flags = CLK_SET_RATE_PARENT | CLK_OPS_PARENT_ENABLE, > }, > }; > > @@ -1543,7 +1543,8 @@ static struct clk_regmap gxbb_vpu_0 = { > .ops = &clk_regmap_gate_ops, > .parent_hws = (const struct clk_hw *[]) { &gxbb_vpu_0_div.hw }, > .num_parents = 1, > - .flags = CLK_SET_RATE_PARENT | CLK_IGNORE_UNUSED, > + .flags = CLK_SET_RATE_PARENT | CLK_IGNORE_UNUSED | > + CLK_SET_RATE_GATE, > }, > }; > > @@ -1591,7 +1592,8 @@ static struct clk_regmap gxbb_vpu_1 = { > .ops = &clk_regmap_gate_ops, > .parent_hws = (const struct clk_hw *[]) { &gxbb_vpu_1_div.hw }, > .num_parents = 1, > - .flags = CLK_SET_RATE_PARENT | CLK_IGNORE_UNUSED, > + .flags = CLK_SET_RATE_PARENT | CLK_IGNORE_UNUSED | > + CLK_SET_RATE_GATE, > }, > }; > > @@ -1613,7 +1615,7 @@ static struct clk_regmap gxbb_vpu = { > &gxbb_vpu_1.hw > }, > .num_parents = 2, > - .flags = CLK_SET_RATE_NO_REPARENT, > + .flags = CLK_SET_RATE_NO_REPARENT | CLK_OPS_PARENT_ENABLE, > }, > }; > > @@ -1674,7 +1676,8 @@ static struct clk_regmap gxbb_vapb_0 = { > &gxbb_vapb_0_div.hw > }, > .num_parents = 1, > - .flags = CLK_SET_RATE_PARENT | CLK_IGNORE_UNUSED, > + .flags = CLK_SET_RATE_PARENT | CLK_IGNORE_UNUSED | > + CLK_SET_RATE_GATE, > }, > }; > > @@ -1726,7 +1729,8 @@ static struct clk_regmap gxbb_vapb_1 = { > &gxbb_vapb_1_div.hw > }, > .num_parents = 1, > - .flags = CLK_SET_RATE_PARENT | CLK_IGNORE_UNUSED, > + .flags = CLK_SET_RATE_PARENT | CLK_IGNORE_UNUSED | > + CLK_SET_RATE_GATE, > }, > }; > > @@ -1748,7 +1752,7 @@ static struct clk_regmap gxbb_vapb_sel = { > &gxbb_vapb_1.hw > }, > .num_parents = 2, > - .flags = CLK_SET_RATE_NO_REPARENT, > + .flags = CLK_SET_RATE_NO_REPARENT | CLK_OPS_PARENT_ENABLE, > }, > }; > > diff --git a/drivers/clk/meson/s4-peripherals.c b/drivers/clk/meson/s4-peripherals.c > index c930cf0614a0..cf10be40141d 100644 > --- a/drivers/clk/meson/s4-peripherals.c > +++ b/drivers/clk/meson/s4-peripherals.c > @@ -1404,7 +1404,7 @@ static struct clk_regmap s4_mali_mux = { > .ops = &clk_regmap_mux_ops, > .parent_hws = s4_mali_parent_hws, > .num_parents = 2, > - .flags = CLK_SET_RATE_PARENT, > + .flags = CLK_SET_RATE_PARENT | CLK_OPS_PARENT_ENABLE, > }, > }; > > @@ -1466,7 +1466,7 @@ static struct clk_regmap s4_vdec_p0 = { > &s4_vdec_p0_div.hw > }, > .num_parents = 1, > - .flags = CLK_SET_RATE_PARENT, > + .flags = CLK_SET_RATE_PARENT | CLK_SET_RATE_GATE, > }, > }; > > @@ -1516,7 +1516,7 @@ static struct clk_regmap s4_vdec_p1 = { > &s4_vdec_p1_div.hw > }, > .num_parents = 1, > - .flags = CLK_SET_RATE_PARENT, > + .flags = CLK_SET_RATE_PARENT | CLK_SET_RATE_GATE, > }, > }; > > @@ -1536,7 +1536,7 @@ static struct clk_regmap s4_vdec_mux = { > .ops = &clk_regmap_mux_ops, > .parent_hws = s4_vdec_mux_parent_hws, > .num_parents = ARRAY_SIZE(s4_vdec_mux_parent_hws), > - .flags = CLK_SET_RATE_PARENT, > + .flags = CLK_SET_RATE_PARENT | CLK_OPS_PARENT_ENABLE, > }, > }; > > @@ -1586,7 +1586,7 @@ static struct clk_regmap s4_hevcf_p0 = { > &s4_hevcf_p0_div.hw > }, > .num_parents = 1, > - .flags = CLK_SET_RATE_PARENT, > + .flags = CLK_SET_RATE_PARENT | CLK_SET_RATE_GATE, > }, > }; > > @@ -1636,7 +1636,7 @@ static struct clk_regmap s4_hevcf_p1 = { > &s4_hevcf_p1_div.hw > }, > .num_parents = 1, > - .flags = CLK_SET_RATE_PARENT, > + .flags = CLK_SET_RATE_PARENT | CLK_SET_RATE_GATE, > }, > }; > > @@ -1656,7 +1656,7 @@ static struct clk_regmap s4_hevcf_mux = { > .ops = &clk_regmap_mux_ops, > .parent_hws = s4_hevcf_mux_parent_hws, > .num_parents = ARRAY_SIZE(s4_hevcf_mux_parent_hws), > - .flags = CLK_SET_RATE_PARENT, > + .flags = CLK_SET_RATE_PARENT | CLK_OPS_PARENT_ENABLE, > }, > }; > > @@ -1712,7 +1712,7 @@ static struct clk_regmap s4_vpu_0 = { > .ops = &clk_regmap_gate_ops, > .parent_hws = (const struct clk_hw *[]) { &s4_vpu_0_div.hw }, > .num_parents = 1, > - .flags = CLK_SET_RATE_PARENT, > + .flags = CLK_SET_RATE_PARENT | CLK_SET_RATE_GATE, > }, > }; > > @@ -1756,7 +1756,7 @@ static struct clk_regmap s4_vpu_1 = { > .ops = &clk_regmap_gate_ops, > .parent_hws = (const struct clk_hw *[]) { &s4_vpu_1_div.hw }, > .num_parents = 1, > - .flags = CLK_SET_RATE_PARENT, > + .flags = CLK_SET_RATE_PARENT | CLK_SET_RATE_GATE, > }, > }; > > @@ -1774,7 +1774,7 @@ static struct clk_regmap s4_vpu = { > &s4_vpu_1.hw, > }, > .num_parents = 2, > - .flags = CLK_SET_RATE_PARENT, > + .flags = CLK_SET_RATE_PARENT | CLK_OPS_PARENT_ENABLE, > }, > }; > > @@ -1921,7 +1921,7 @@ static struct clk_regmap s4_vpu_clkc_p0 = { > &s4_vpu_clkc_p0_div.hw > }, > .num_parents = 1, > - .flags = CLK_SET_RATE_PARENT, > + .flags = CLK_SET_RATE_PARENT | CLK_SET_RATE_GATE, > }, > }; > > @@ -1969,7 +1969,7 @@ static struct clk_regmap s4_vpu_clkc_p1 = { > &s4_vpu_clkc_p1_div.hw > }, > .num_parents = 1, > - .flags = CLK_SET_RATE_PARENT, > + .flags = CLK_SET_RATE_PARENT | CLK_SET_RATE_GATE, > }, > }; > > @@ -1989,7 +1989,7 @@ static struct clk_regmap s4_vpu_clkc_mux = { > .ops = &clk_regmap_mux_ops, > .parent_hws = s4_vpu_mux_parent_hws, > .num_parents = ARRAY_SIZE(s4_vpu_mux_parent_hws), > - .flags = CLK_SET_RATE_PARENT, > + .flags = CLK_SET_RATE_PARENT | CLK_OPS_PARENT_ENABLE, > }, > }; > > @@ -2049,7 +2049,7 @@ static struct clk_regmap s4_vapb_0 = { > &s4_vapb_0_div.hw > }, > .num_parents = 1, > - .flags = CLK_SET_RATE_PARENT, > + .flags = CLK_SET_RATE_PARENT | CLK_SET_RATE_GATE, > }, > }; > > @@ -2097,7 +2097,7 @@ static struct clk_regmap s4_vapb_1 = { > &s4_vapb_1_div.hw > }, > .num_parents = 1, > - .flags = CLK_SET_RATE_PARENT, > + .flags = CLK_SET_RATE_PARENT | CLK_SET_RATE_GATE, > }, > }; > > @@ -2115,7 +2115,7 @@ static struct clk_regmap s4_vapb = { > &s4_vapb_1.hw > }, > .num_parents = 2, > - .flags = CLK_SET_RATE_PARENT, > + .flags = CLK_SET_RATE_PARENT | CLK_OPS_PARENT_ENABLE, > }, > };
Hello, On Sun, Sep 29, 2024 at 8:10 AM Chuan Liu via B4 Relay <devnull+chuan.liu.amlogic.com@kernel.org> wrote: > > From: Chuan Liu <chuan.liu@amlogic.com> > > glitch free mux has two clock channels (channel 0 and channel 1) with > the same configuration. When the frequency needs to be changed, the two > channels ping-pong to ensure clock continuity and suppress glitch. You describe the solution to this below: > Add flag CLK_SET_RATE_GATE to channels 0 and 1 to implement Ping-Pong > switchover to suppress glitch. It would be great to have this change in a separate patch. The clocks to which you're adding CLK_SET_RATE_GATE aren't switched at runtime in mainline kernels (at least I think so). > Channel 0 of glitch free mux is not only the clock source for the mux, > but also the working clock for glitch free mux. Therefore, when glitch > free mux switches, it is necessary to ensure that channel 0 has a clock > input, otherwise glitch free mux will not work and cannot switch to the > target channel. [...] > glitch free mux Add flag CLK_OPS_PARENT_ENABLE to ensure that channel 0 > has clock input when switching channels. This describes a second problem. I think it's best to have this in a separate commit/patch. Also you're updating some mali clocks (e.g. on G12 and GX) but not all of them (Meson8b for example is missing). I still have some questions to the CLK_OPS_PARENT_ENABLE approach - please share your findings on this. There's multiple clocks involved in a glitch-free mux hierarchy: - a number of clock inputs (e.g. fclk, xtal, ...) - two muxes (one for every channel of the glitch-free mux) - two dividers (one for every channel of the glitch-free mux) - two gates (one for every channel of the glitch-free mux) - the glitch-free mux When switching from channel 0 (which is active and enabled) CCF (common clock framework) will: a) on channel 1: - find the best input clock - choose the best input clock in the mux - set the divider - enable the gate b) switch the glitch-free mux c) on channel 2: - disable the gate To me it's not clear at which level the problem occurs (glitch-free mux, gate, divider, mux, input clock). Also I don't understand why enabling the clocks with CLK_OPS_PARENT_ENABLE solves any problem since CCF is doing things automatically for us. Can you please explain (preferably with an example) what problem is solved with this approach? Last but not least: if we're running into bugs when CLK_OPS_PARENT_ENABLE is missing then that patch should carry a Fixes tag. Best regards, Martin
Hi Martin, On 2024/10/1 4:08, Martin Blumenstingl wrote: > [ EXTERNAL EMAIL ] > > Hello, > > On Sun, Sep 29, 2024 at 8:10 AM Chuan Liu via B4 Relay > <devnull+chuan.liu.amlogic.com@kernel.org> wrote: >> From: Chuan Liu <chuan.liu@amlogic.com> >> >> glitch free mux has two clock channels (channel 0 and channel 1) with >> the same configuration. When the frequency needs to be changed, the two >> channels ping-pong to ensure clock continuity and suppress glitch. > You describe the solution to this below: >> Add flag CLK_SET_RATE_GATE to channels 0 and 1 to implement Ping-Pong >> switchover to suppress glitch. > It would be great to have this change in a separate patch. > The clocks to which you're adding CLK_SET_RATE_GATE aren't switched at > runtime in mainline kernels (at least I think so). Okay, I will separate it into two patches and submit it in the next version. > >> Channel 0 of glitch free mux is not only the clock source for the mux, >> but also the working clock for glitch free mux. Therefore, when glitch >> free mux switches, it is necessary to ensure that channel 0 has a clock >> input, otherwise glitch free mux will not work and cannot switch to the >> target channel. > [...] >> glitch free mux Add flag CLK_OPS_PARENT_ENABLE to ensure that channel 0 >> has clock input when switching channels. > This describes a second problem. I think it's best to have this in a > separate commit/patch. > Also you're updating some mali clocks (e.g. on G12 and GX) but not all > of them (Meson8b for example is missing). Yes, M8 missed it, I will complete it in the next version. > > I still have some questions to the CLK_OPS_PARENT_ENABLE approach - > please share your findings on this. > > There's multiple clocks involved in a glitch-free mux hierarchy: > - a number of clock inputs (e.g. fclk, xtal, ...) > - two muxes (one for every channel of the glitch-free mux) > - two dividers (one for every channel of the glitch-free mux) > - two gates (one for every channel of the glitch-free mux) > - the glitch-free mux > > When switching from channel 0 (which is active and enabled) CCF > (common clock framework) will: > a) on channel 1: > - find the best input clock > - choose the best input clock in the mux > - set the divider > - enable the gate > b) switch the glitch-free mux > c) on channel 2: > - disable the gate > > To me it's not clear at which level the problem occurs (glitch-free > mux, gate, divider, mux, input clock). > Also I don't understand why enabling the clocks with > CLK_OPS_PARENT_ENABLE solves any problem since CCF is doing things > automatically for us. > Can you please explain (preferably with an example) what problem is > solved with this approach? If CLK_OPS_PARENT_ENABLE is configured in mux, 'new_parent' and 'old_parent' will be enabled first when __clk_set_parent_before() is called. And disable them at __clk_set_parent_after(). Our glitch free only has two clock sources, so adding this flag ensures that both channels 0 and 1 are enabled when mux switches. In fact, we just need to make sure that channel 0 is enabled. The purpose of CLK_OPS_PARENT_ENABLE may not be to solve our situation, but adding this flag does solve our current problem. > > Last but not least: if we're running into bugs when > CLK_OPS_PARENT_ENABLE is missing then that patch should carry a Fixes > tag. Thanks for the heads-up. I'll keep an eye on it in the next version. > > Best regards, > Martin
On Tue 08 Oct 2024 at 13:44, Chuan Liu <chuan.liu@amlogic.com> wrote: > Hi Martin, > > > On 2024/10/1 4:08, Martin Blumenstingl wrote: >> [ EXTERNAL EMAIL ] >> >> Hello, >> >> On Sun, Sep 29, 2024 at 8:10 AM Chuan Liu via B4 Relay >> <devnull+chuan.liu.amlogic.com@kernel.org> wrote: >>> From: Chuan Liu <chuan.liu@amlogic.com> >>> >>> glitch free mux has two clock channels (channel 0 and channel 1) with >>> the same configuration. When the frequency needs to be changed, the two >>> channels ping-pong to ensure clock continuity and suppress glitch. >> You describe the solution to this below: >>> Add flag CLK_SET_RATE_GATE to channels 0 and 1 to implement Ping-Pong >>> switchover to suppress glitch. >> It would be great to have this change in a separate patch. >> The clocks to which you're adding CLK_SET_RATE_GATE aren't switched at >> runtime in mainline kernels (at least I think so). > > > Okay, I will separate it into two patches and submit it in the next version. > > >> >>> Channel 0 of glitch free mux is not only the clock source for the mux, >>> but also the working clock for glitch free mux. Therefore, when glitch >>> free mux switches, it is necessary to ensure that channel 0 has a clock >>> input, otherwise glitch free mux will not work and cannot switch to the >>> target channel. >> [...] >>> glitch free mux Add flag CLK_OPS_PARENT_ENABLE to ensure that channel 0 >>> has clock input when switching channels. >> This describes a second problem. I think it's best to have this in a >> separate commit/patch. >> Also you're updating some mali clocks (e.g. on G12 and GX) but not all >> of them (Meson8b for example is missing). > > > Yes, M8 missed it, I will complete it in the next version. > > >> >> I still have some questions to the CLK_OPS_PARENT_ENABLE approach - >> please share your findings on this. >> >> There's multiple clocks involved in a glitch-free mux hierarchy: >> - a number of clock inputs (e.g. fclk, xtal, ...) >> - two muxes (one for every channel of the glitch-free mux) >> - two dividers (one for every channel of the glitch-free mux) >> - two gates (one for every channel of the glitch-free mux) >> - the glitch-free mux >> >> When switching from channel 0 (which is active and enabled) CCF >> (common clock framework) will: >> a) on channel 1: >> - find the best input clock >> - choose the best input clock in the mux >> - set the divider >> - enable the gate >> b) switch the glitch-free mux >> c) on channel 2: >> - disable the gate >> >> To me it's not clear at which level the problem occurs (glitch-free >> mux, gate, divider, mux, input clock). >> Also I don't understand why enabling the clocks with >> CLK_OPS_PARENT_ENABLE solves any problem since CCF is doing things >> automatically for us. >> Can you please explain (preferably with an example) what problem is >> solved with this approach? > > > If CLK_OPS_PARENT_ENABLE is configured in mux, 'new_parent' and > 'old_parent' will be enabled first when __clk_set_parent_before() is > called. And disable them at __clk_set_parent_after(). Our glitch free > only has two clock sources, so adding this flag ensures that both > channels 0 and 1 are enabled when mux switches. > > In fact, we just need to make sure that channel 0 is enabled. The > purpose of CLK_OPS_PARENT_ENABLE may not be to solve our situation, > but adding this flag does solve our current problem. This is last point is important. It is OK to use a side effect of CLK_OPS_PARENT_ENABLE but it needs to be documented somehow, so what really matters is still known 2y from now. Make sure the information appears in the code comments at least once. > > >> >> Last but not least: if we're running into bugs when >> CLK_OPS_PARENT_ENABLE is missing then that patch should carry a Fixes >> tag. > > > Thanks for the heads-up. I'll keep an eye on it in the next version. > > >> >> Best regards, >> Martin
diff --git a/drivers/clk/meson/a1-peripherals.c b/drivers/clk/meson/a1-peripherals.c index 7aa6abb2eb1f..7f515e002adb 100644 --- a/drivers/clk/meson/a1-peripherals.c +++ b/drivers/clk/meson/a1-peripherals.c @@ -423,7 +423,7 @@ static struct clk_regmap dspa_a = { &dspa_a_div.hw }, .num_parents = 1, - .flags = CLK_SET_RATE_PARENT, + .flags = CLK_SET_RATE_PARENT | CLK_SET_RATE_GATE, }, }; @@ -471,7 +471,7 @@ static struct clk_regmap dspa_b = { &dspa_b_div.hw }, .num_parents = 1, - .flags = CLK_SET_RATE_PARENT, + .flags = CLK_SET_RATE_PARENT | CLK_SET_RATE_GATE, }, }; @@ -489,7 +489,7 @@ static struct clk_regmap dspa_sel = { &dspa_b.hw, }, .num_parents = 2, - .flags = CLK_SET_RATE_PARENT, + .flags = CLK_SET_RATE_PARENT | CLK_OPS_PARENT_ENABLE, }, }; @@ -569,7 +569,7 @@ static struct clk_regmap dspb_a = { &dspb_a_div.hw }, .num_parents = 1, - .flags = CLK_SET_RATE_PARENT, + .flags = CLK_SET_RATE_PARENT | CLK_SET_RATE_GATE, }, }; @@ -617,7 +617,7 @@ static struct clk_regmap dspb_b = { &dspb_b_div.hw }, .num_parents = 1, - .flags = CLK_SET_RATE_PARENT, + .flags = CLK_SET_RATE_PARENT | CLK_SET_RATE_GATE, }, }; @@ -635,7 +635,7 @@ static struct clk_regmap dspb_sel = { &dspb_b.hw, }, .num_parents = 2, - .flags = CLK_SET_RATE_PARENT, + .flags = CLK_SET_RATE_PARENT | CLK_OPS_PARENT_ENABLE, }, }; diff --git a/drivers/clk/meson/axg.c b/drivers/clk/meson/axg.c index 1b08daf579b2..e2d3266f4b45 100644 --- a/drivers/clk/meson/axg.c +++ b/drivers/clk/meson/axg.c @@ -1077,7 +1077,8 @@ static struct clk_regmap axg_vpu_0 = { * We want to avoid CCF to disable the VPU clock if * display has been set by Bootloader */ - .flags = CLK_SET_RATE_PARENT | CLK_IGNORE_UNUSED, + .flags = CLK_SET_RATE_PARENT | CLK_IGNORE_UNUSED | + CLK_SET_RATE_GATE, }, }; @@ -1126,7 +1127,8 @@ static struct clk_regmap axg_vpu_1 = { * We want to avoid CCF to disable the VPU clock if * display has been set by Bootloader */ - .flags = CLK_SET_RATE_PARENT | CLK_IGNORE_UNUSED, + .flags = CLK_SET_RATE_PARENT | CLK_IGNORE_UNUSED | + CLK_SET_RATE_GATE, }, }; @@ -1144,7 +1146,7 @@ static struct clk_regmap axg_vpu = { &axg_vpu_1.hw }, .num_parents = 2, - .flags = CLK_SET_RATE_NO_REPARENT, + .flags = CLK_SET_RATE_NO_REPARENT | CLK_OPS_PARENT_ENABLE, }, }; @@ -1194,7 +1196,8 @@ static struct clk_regmap axg_vapb_0 = { &axg_vapb_0_div.hw }, .num_parents = 1, - .flags = CLK_SET_RATE_PARENT | CLK_IGNORE_UNUSED, + .flags = CLK_SET_RATE_PARENT | CLK_IGNORE_UNUSED | + CLK_SET_RATE_GATE, }, }; @@ -1242,7 +1245,8 @@ static struct clk_regmap axg_vapb_1 = { &axg_vapb_1_div.hw }, .num_parents = 1, - .flags = CLK_SET_RATE_PARENT | CLK_IGNORE_UNUSED, + .flags = CLK_SET_RATE_PARENT | CLK_IGNORE_UNUSED | + CLK_SET_RATE_GATE, }, }; @@ -1260,7 +1264,7 @@ static struct clk_regmap axg_vapb_sel = { &axg_vapb_1.hw }, .num_parents = 2, - .flags = CLK_SET_RATE_NO_REPARENT, + .flags = CLK_SET_RATE_NO_REPARENT | CLK_OPS_PARENT_ENABLE, }, }; diff --git a/drivers/clk/meson/c3-peripherals.c b/drivers/clk/meson/c3-peripherals.c index 7dcbf4ebee07..27343a73a521 100644 --- a/drivers/clk/meson/c3-peripherals.c +++ b/drivers/clk/meson/c3-peripherals.c @@ -1364,7 +1364,7 @@ static struct clk_regmap hcodec_0 = { &hcodec_0_div.hw }, .num_parents = 1, - .flags = CLK_SET_RATE_PARENT, + .flags = CLK_SET_RATE_PARENT | CLK_SET_RATE_GATE, }, }; @@ -1411,7 +1411,7 @@ static struct clk_regmap hcodec_1 = { &hcodec_1_div.hw }, .num_parents = 1, - .flags = CLK_SET_RATE_PARENT, + .flags = CLK_SET_RATE_PARENT | CLK_SET_RATE_GATE, }, }; @@ -1431,7 +1431,7 @@ static struct clk_regmap hcodec = { .ops = &clk_regmap_mux_ops, .parent_data = hcodec_parent_data, .num_parents = ARRAY_SIZE(hcodec_parent_data), - .flags = CLK_SET_RATE_PARENT, + .flags = CLK_SET_RATE_PARENT | CLK_OPS_PARENT_ENABLE, }, }; diff --git a/drivers/clk/meson/g12a.c b/drivers/clk/meson/g12a.c index d3539fe9f7af..21a25001e904 100644 --- a/drivers/clk/meson/g12a.c +++ b/drivers/clk/meson/g12a.c @@ -2746,7 +2746,8 @@ static struct clk_regmap g12a_vpu_0 = { .ops = &clk_regmap_gate_ops, .parent_hws = (const struct clk_hw *[]) { &g12a_vpu_0_div.hw }, .num_parents = 1, - .flags = CLK_SET_RATE_PARENT | CLK_IGNORE_UNUSED, + .flags = CLK_SET_RATE_PARENT | CLK_IGNORE_UNUSED | + CLK_SET_RATE_GATE, }, }; @@ -2790,7 +2791,8 @@ static struct clk_regmap g12a_vpu_1 = { .ops = &clk_regmap_gate_ops, .parent_hws = (const struct clk_hw *[]) { &g12a_vpu_1_div.hw }, .num_parents = 1, - .flags = CLK_SET_RATE_PARENT | CLK_IGNORE_UNUSED, + .flags = CLK_SET_RATE_PARENT | CLK_IGNORE_UNUSED | + CLK_SET_RATE_GATE, }, }; @@ -2812,7 +2814,7 @@ static struct clk_regmap g12a_vpu = { &g12a_vpu_1.hw, }, .num_parents = 2, - .flags = CLK_SET_RATE_NO_REPARENT, + .flags = CLK_SET_RATE_NO_REPARENT | CLK_OPS_PARENT_ENABLE, }, }; @@ -3035,7 +3037,8 @@ static struct clk_regmap g12a_vapb_0 = { &g12a_vapb_0_div.hw }, .num_parents = 1, - .flags = CLK_SET_RATE_PARENT | CLK_IGNORE_UNUSED, + .flags = CLK_SET_RATE_PARENT | CLK_IGNORE_UNUSED | + CLK_SET_RATE_GATE, }, }; @@ -3083,7 +3086,8 @@ static struct clk_regmap g12a_vapb_1 = { &g12a_vapb_1_div.hw }, .num_parents = 1, - .flags = CLK_SET_RATE_PARENT | CLK_IGNORE_UNUSED, + .flags = CLK_SET_RATE_PARENT | CLK_IGNORE_UNUSED | + CLK_SET_RATE_GATE, }, }; @@ -3105,7 +3109,7 @@ static struct clk_regmap g12a_vapb_sel = { &g12a_vapb_1.hw, }, .num_parents = 2, - .flags = CLK_SET_RATE_NO_REPARENT, + .flags = CLK_SET_RATE_NO_REPARENT | CLK_OPS_PARENT_ENABLE, }, }; @@ -4039,7 +4043,7 @@ static struct clk_regmap g12a_mali = { .ops = &clk_regmap_mux_ops, .parent_hws = g12a_mali_parent_hws, .num_parents = 2, - .flags = CLK_SET_RATE_PARENT, + .flags = CLK_SET_RATE_PARENT | CLK_OPS_PARENT_ENABLE, }, }; diff --git a/drivers/clk/meson/gxbb.c b/drivers/clk/meson/gxbb.c index 262c318edbd5..812b3e20c366 100644 --- a/drivers/clk/meson/gxbb.c +++ b/drivers/clk/meson/gxbb.c @@ -1132,7 +1132,7 @@ static struct clk_regmap gxbb_mali = { .ops = &clk_regmap_mux_ops, .parent_hws = gxbb_mali_parent_hws, .num_parents = 2, - .flags = CLK_SET_RATE_PARENT, + .flags = CLK_SET_RATE_PARENT | CLK_OPS_PARENT_ENABLE, }, }; @@ -1543,7 +1543,8 @@ static struct clk_regmap gxbb_vpu_0 = { .ops = &clk_regmap_gate_ops, .parent_hws = (const struct clk_hw *[]) { &gxbb_vpu_0_div.hw }, .num_parents = 1, - .flags = CLK_SET_RATE_PARENT | CLK_IGNORE_UNUSED, + .flags = CLK_SET_RATE_PARENT | CLK_IGNORE_UNUSED | + CLK_SET_RATE_GATE, }, }; @@ -1591,7 +1592,8 @@ static struct clk_regmap gxbb_vpu_1 = { .ops = &clk_regmap_gate_ops, .parent_hws = (const struct clk_hw *[]) { &gxbb_vpu_1_div.hw }, .num_parents = 1, - .flags = CLK_SET_RATE_PARENT | CLK_IGNORE_UNUSED, + .flags = CLK_SET_RATE_PARENT | CLK_IGNORE_UNUSED | + CLK_SET_RATE_GATE, }, }; @@ -1613,7 +1615,7 @@ static struct clk_regmap gxbb_vpu = { &gxbb_vpu_1.hw }, .num_parents = 2, - .flags = CLK_SET_RATE_NO_REPARENT, + .flags = CLK_SET_RATE_NO_REPARENT | CLK_OPS_PARENT_ENABLE, }, }; @@ -1674,7 +1676,8 @@ static struct clk_regmap gxbb_vapb_0 = { &gxbb_vapb_0_div.hw }, .num_parents = 1, - .flags = CLK_SET_RATE_PARENT | CLK_IGNORE_UNUSED, + .flags = CLK_SET_RATE_PARENT | CLK_IGNORE_UNUSED | + CLK_SET_RATE_GATE, }, }; @@ -1726,7 +1729,8 @@ static struct clk_regmap gxbb_vapb_1 = { &gxbb_vapb_1_div.hw }, .num_parents = 1, - .flags = CLK_SET_RATE_PARENT | CLK_IGNORE_UNUSED, + .flags = CLK_SET_RATE_PARENT | CLK_IGNORE_UNUSED | + CLK_SET_RATE_GATE, }, }; @@ -1748,7 +1752,7 @@ static struct clk_regmap gxbb_vapb_sel = { &gxbb_vapb_1.hw }, .num_parents = 2, - .flags = CLK_SET_RATE_NO_REPARENT, + .flags = CLK_SET_RATE_NO_REPARENT | CLK_OPS_PARENT_ENABLE, }, }; diff --git a/drivers/clk/meson/s4-peripherals.c b/drivers/clk/meson/s4-peripherals.c index c930cf0614a0..cf10be40141d 100644 --- a/drivers/clk/meson/s4-peripherals.c +++ b/drivers/clk/meson/s4-peripherals.c @@ -1404,7 +1404,7 @@ static struct clk_regmap s4_mali_mux = { .ops = &clk_regmap_mux_ops, .parent_hws = s4_mali_parent_hws, .num_parents = 2, - .flags = CLK_SET_RATE_PARENT, + .flags = CLK_SET_RATE_PARENT | CLK_OPS_PARENT_ENABLE, }, }; @@ -1466,7 +1466,7 @@ static struct clk_regmap s4_vdec_p0 = { &s4_vdec_p0_div.hw }, .num_parents = 1, - .flags = CLK_SET_RATE_PARENT, + .flags = CLK_SET_RATE_PARENT | CLK_SET_RATE_GATE, }, }; @@ -1516,7 +1516,7 @@ static struct clk_regmap s4_vdec_p1 = { &s4_vdec_p1_div.hw }, .num_parents = 1, - .flags = CLK_SET_RATE_PARENT, + .flags = CLK_SET_RATE_PARENT | CLK_SET_RATE_GATE, }, }; @@ -1536,7 +1536,7 @@ static struct clk_regmap s4_vdec_mux = { .ops = &clk_regmap_mux_ops, .parent_hws = s4_vdec_mux_parent_hws, .num_parents = ARRAY_SIZE(s4_vdec_mux_parent_hws), - .flags = CLK_SET_RATE_PARENT, + .flags = CLK_SET_RATE_PARENT | CLK_OPS_PARENT_ENABLE, }, }; @@ -1586,7 +1586,7 @@ static struct clk_regmap s4_hevcf_p0 = { &s4_hevcf_p0_div.hw }, .num_parents = 1, - .flags = CLK_SET_RATE_PARENT, + .flags = CLK_SET_RATE_PARENT | CLK_SET_RATE_GATE, }, }; @@ -1636,7 +1636,7 @@ static struct clk_regmap s4_hevcf_p1 = { &s4_hevcf_p1_div.hw }, .num_parents = 1, - .flags = CLK_SET_RATE_PARENT, + .flags = CLK_SET_RATE_PARENT | CLK_SET_RATE_GATE, }, }; @@ -1656,7 +1656,7 @@ static struct clk_regmap s4_hevcf_mux = { .ops = &clk_regmap_mux_ops, .parent_hws = s4_hevcf_mux_parent_hws, .num_parents = ARRAY_SIZE(s4_hevcf_mux_parent_hws), - .flags = CLK_SET_RATE_PARENT, + .flags = CLK_SET_RATE_PARENT | CLK_OPS_PARENT_ENABLE, }, }; @@ -1712,7 +1712,7 @@ static struct clk_regmap s4_vpu_0 = { .ops = &clk_regmap_gate_ops, .parent_hws = (const struct clk_hw *[]) { &s4_vpu_0_div.hw }, .num_parents = 1, - .flags = CLK_SET_RATE_PARENT, + .flags = CLK_SET_RATE_PARENT | CLK_SET_RATE_GATE, }, }; @@ -1756,7 +1756,7 @@ static struct clk_regmap s4_vpu_1 = { .ops = &clk_regmap_gate_ops, .parent_hws = (const struct clk_hw *[]) { &s4_vpu_1_div.hw }, .num_parents = 1, - .flags = CLK_SET_RATE_PARENT, + .flags = CLK_SET_RATE_PARENT | CLK_SET_RATE_GATE, }, }; @@ -1774,7 +1774,7 @@ static struct clk_regmap s4_vpu = { &s4_vpu_1.hw, }, .num_parents = 2, - .flags = CLK_SET_RATE_PARENT, + .flags = CLK_SET_RATE_PARENT | CLK_OPS_PARENT_ENABLE, }, }; @@ -1921,7 +1921,7 @@ static struct clk_regmap s4_vpu_clkc_p0 = { &s4_vpu_clkc_p0_div.hw }, .num_parents = 1, - .flags = CLK_SET_RATE_PARENT, + .flags = CLK_SET_RATE_PARENT | CLK_SET_RATE_GATE, }, }; @@ -1969,7 +1969,7 @@ static struct clk_regmap s4_vpu_clkc_p1 = { &s4_vpu_clkc_p1_div.hw }, .num_parents = 1, - .flags = CLK_SET_RATE_PARENT, + .flags = CLK_SET_RATE_PARENT | CLK_SET_RATE_GATE, }, }; @@ -1989,7 +1989,7 @@ static struct clk_regmap s4_vpu_clkc_mux = { .ops = &clk_regmap_mux_ops, .parent_hws = s4_vpu_mux_parent_hws, .num_parents = ARRAY_SIZE(s4_vpu_mux_parent_hws), - .flags = CLK_SET_RATE_PARENT, + .flags = CLK_SET_RATE_PARENT | CLK_OPS_PARENT_ENABLE, }, }; @@ -2049,7 +2049,7 @@ static struct clk_regmap s4_vapb_0 = { &s4_vapb_0_div.hw }, .num_parents = 1, - .flags = CLK_SET_RATE_PARENT, + .flags = CLK_SET_RATE_PARENT | CLK_SET_RATE_GATE, }, }; @@ -2097,7 +2097,7 @@ static struct clk_regmap s4_vapb_1 = { &s4_vapb_1_div.hw }, .num_parents = 1, - .flags = CLK_SET_RATE_PARENT, + .flags = CLK_SET_RATE_PARENT | CLK_SET_RATE_GATE, }, }; @@ -2115,7 +2115,7 @@ static struct clk_regmap s4_vapb = { &s4_vapb_1.hw }, .num_parents = 2, - .flags = CLK_SET_RATE_PARENT, + .flags = CLK_SET_RATE_PARENT | CLK_OPS_PARENT_ENABLE, }, };