[v3,3/3] clk: mediatek: mt8188-topckgen: Refactor parents for top_dp/edp muxes
Commit Message
The top_dp and top_edp muxes can be both parented to either TVDPLL1
or TVDPLL2, two identically specced PLLs for the specific purpose of
giving out pixel clock: this becomes a problem when the MediaTek
DisplayPort Interface (DPI) driver tries to set the pixel clock rate.
In the usecase of two simultaneous outputs (using two controllers),
it was seen that one of the displays would sometimes display garbled
output (if any at all) and this was because:
- top_edp was set to TVDPLL1, outputting X GHz
- top_dp was set to TVDPLL2, outputting Y GHz
- mtk_dpi calls clk_set_rate(top_edp, Z GHz)
- top_dp is switched to TVDPLL1
- TVDPLL1 changes its rate, top_edp outputs the wrong rate.
- eDP display is garbled
To solve this issue, remove all TVDPLL1 parents from `top_dp` and
all TVDPLL2 parents from `top_edp`, plus, necessarily switch both
clocks to use the new MUX_GATE_CLR_SET_UPD_INDEXED() macro to be
able to use the right bit index for the new parents list.
Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
---
drivers/clk/mediatek/clk-mt8188-topckgen.c | 27 +++++++++++-----------
1 file changed, 14 insertions(+), 13 deletions(-)
Comments
On 03/11/2023 11:25, AngeloGioacchino Del Regno wrote:
> The top_dp and top_edp muxes can be both parented to either TVDPLL1
> or TVDPLL2, two identically specced PLLs for the specific purpose of
> giving out pixel clock: this becomes a problem when the MediaTek
> DisplayPort Interface (DPI) driver tries to set the pixel clock rate.
>
> In the usecase of two simultaneous outputs (using two controllers),
> it was seen that one of the displays would sometimes display garbled
> output (if any at all) and this was because:
> - top_edp was set to TVDPLL1, outputting X GHz
> - top_dp was set to TVDPLL2, outputting Y GHz
> - mtk_dpi calls clk_set_rate(top_edp, Z GHz)
> - top_dp is switched to TVDPLL1
> - TVDPLL1 changes its rate, top_edp outputs the wrong rate.
> - eDP display is garbled
>
> To solve this issue, remove all TVDPLL1 parents from `top_dp` and
> all TVDPLL2 parents from `top_edp`, plus, necessarily switch both
> clocks to use the new MUX_GATE_CLR_SET_UPD_INDEXED() macro to be
> able to use the right bit index for the new parents list.
Reviewed-by: Alexandre Mergnat <amergnat@baylibre.com>
On Fri, Nov 3, 2023 at 6:25 PM AngeloGioacchino Del Regno
<angelogioacchino.delregno@collabora.com> wrote:
>
> The top_dp and top_edp muxes can be both parented to either TVDPLL1
> or TVDPLL2, two identically specced PLLs for the specific purpose of
> giving out pixel clock: this becomes a problem when the MediaTek
> DisplayPort Interface (DPI) driver tries to set the pixel clock rate.
>
> In the usecase of two simultaneous outputs (using two controllers),
> it was seen that one of the displays would sometimes display garbled
> output (if any at all) and this was because:
> - top_edp was set to TVDPLL1, outputting X GHz
> - top_dp was set to TVDPLL2, outputting Y GHz
> - mtk_dpi calls clk_set_rate(top_edp, Z GHz)
> - top_dp is switched to TVDPLL1
> - TVDPLL1 changes its rate, top_edp outputs the wrong rate.
> - eDP display is garbled
>
> To solve this issue, remove all TVDPLL1 parents from `top_dp` and
> all TVDPLL2 parents from `top_edp`, plus, necessarily switch both
> clocks to use the new MUX_GATE_CLR_SET_UPD_INDEXED() macro to be
> able to use the right bit index for the new parents list.
>
> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Chen-Yu Tsai <wenst@chromium.org>
On Fri, Nov 3, 2023 at 6:25 PM AngeloGioacchino Del Regno
<angelogioacchino.delregno@collabora.com> wrote:
>
> The top_dp and top_edp muxes can be both parented to either TVDPLL1
> or TVDPLL2, two identically specced PLLs for the specific purpose of
> giving out pixel clock: this becomes a problem when the MediaTek
> DisplayPort Interface (DPI) driver tries to set the pixel clock rate.
>
> In the usecase of two simultaneous outputs (using two controllers),
> it was seen that one of the displays would sometimes display garbled
> output (if any at all) and this was because:
> - top_edp was set to TVDPLL1, outputting X GHz
> - top_dp was set to TVDPLL2, outputting Y GHz
> - mtk_dpi calls clk_set_rate(top_edp, Z GHz)
> - top_dp is switched to TVDPLL1
> - TVDPLL1 changes its rate, top_edp outputs the wrong rate.
> - eDP display is garbled
>
> To solve this issue, remove all TVDPLL1 parents from `top_dp` and
> all TVDPLL2 parents from `top_edp`, plus, necessarily switch both
> clocks to use the new MUX_GATE_CLR_SET_UPD_INDEXED() macro to be
> able to use the right bit index for the new parents list.
>
> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Tested on MT8188 with a Type-C -> DP adapter to an extended display
Gigabyte M32U.
The DP output reacts smoothly to resolution switch and refresh rate
change, and the internal eDP output also never freezes.
Reviewed-by: Fei Shao <fshao@chromium.org>
Tested-by: Fei Shao <fshao@chromium.org>
Quoting AngeloGioacchino Del Regno (2023-11-03 03:25:33)
> The top_dp and top_edp muxes can be both parented to either TVDPLL1
> or TVDPLL2, two identically specced PLLs for the specific purpose of
> giving out pixel clock: this becomes a problem when the MediaTek
> DisplayPort Interface (DPI) driver tries to set the pixel clock rate.
>
> In the usecase of two simultaneous outputs (using two controllers),
> it was seen that one of the displays would sometimes display garbled
> output (if any at all) and this was because:
> - top_edp was set to TVDPLL1, outputting X GHz
> - top_dp was set to TVDPLL2, outputting Y GHz
> - mtk_dpi calls clk_set_rate(top_edp, Z GHz)
> - top_dp is switched to TVDPLL1
> - TVDPLL1 changes its rate, top_edp outputs the wrong rate.
> - eDP display is garbled
>
> To solve this issue, remove all TVDPLL1 parents from `top_dp` and
> all TVDPLL2 parents from `top_edp`, plus, necessarily switch both
> clocks to use the new MUX_GATE_CLR_SET_UPD_INDEXED() macro to be
> able to use the right bit index for the new parents list.
>
> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
> ---
Applied to clk-next
@@ -475,29 +475,28 @@ static const char * const sspm_parents[] = {
"mainpll_d4_d2"
};
+/*
+ * Both DP/eDP can be parented to TVDPLL1 and TVDPLL2, but we force using
+ * TVDPLL1 on eDP and TVDPLL2 on DP to avoid changing the "other" PLL rate
+ * in dual output case, which would lead to corruption of functionality loss.
+ */
static const char * const dp_parents[] = {
"clk26m",
- "tvdpll1_d2",
"tvdpll2_d2",
- "tvdpll1_d4",
"tvdpll2_d4",
- "tvdpll1_d8",
"tvdpll2_d8",
- "tvdpll1_d16",
"tvdpll2_d16"
};
+static const u8 dp_parents_idx[] = { 0, 2, 4, 6, 8 };
static const char * const edp_parents[] = {
"clk26m",
"tvdpll1_d2",
- "tvdpll2_d2",
"tvdpll1_d4",
- "tvdpll2_d4",
"tvdpll1_d8",
- "tvdpll2_d8",
- "tvdpll1_d16",
- "tvdpll2_d16"
+ "tvdpll1_d16"
};
+static const u8 edp_parents_idx[] = { 0, 1, 3, 5, 7 };
static const char * const dpi_parents[] = {
"clk26m",
@@ -1038,10 +1037,12 @@ static const struct mtk_mux top_mtk_muxes[] = {
MUX_GATE_CLR_SET_UPD(CLK_TOP_SSPM, "top_sspm",
sspm_parents, 0x080, 0x084, 0x088, 24, 4, 31, 0x08, 3),
/* CLK_CFG_9 */
- MUX_GATE_CLR_SET_UPD(CLK_TOP_DP, "top_dp",
- dp_parents, 0x08C, 0x090, 0x094, 0, 4, 7, 0x08, 4),
- MUX_GATE_CLR_SET_UPD(CLK_TOP_EDP, "top_edp",
- edp_parents, 0x08C, 0x090, 0x094, 8, 4, 15, 0x08, 5),
+ MUX_GATE_CLR_SET_UPD_INDEXED(CLK_TOP_DP, "top_dp",
+ dp_parents, dp_parents_idx, 0x08C, 0x090, 0x094,
+ 0, 4, 7, 0x08, 4),
+ MUX_GATE_CLR_SET_UPD_INDEXED(CLK_TOP_EDP, "top_edp",
+ edp_parents, edp_parents_idx, 0x08C, 0x090, 0x094,
+ 8, 4, 15, 0x08, 5),
MUX_GATE_CLR_SET_UPD(CLK_TOP_DPI, "top_dpi",
dpi_parents, 0x08C, 0x090, 0x094, 16, 4, 23, 0x08, 6),
MUX_GATE_CLR_SET_UPD(CLK_TOP_DISP_PWM0, "top_disp_pwm0",