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Message-ID: <9411928.T7Z3S40VBb@senjougahara>
Date: Thu, 15 Jan 2026 16:02:46 +0900
From: Mikko Perttunen <mperttunen@...dia.com>
To: Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
Conor Dooley <conor+dt@...nel.org>,
Thierry Reding <thierry.reding@...il.com>,
Thierry Reding <treding@...dia.com>, Jonathan Hunter <jonathanh@...dia.com>,
Prashant Gaikwad <pgaikwad@...dia.com>,
Michael Turquette <mturquette@...libre.com>, Stephen Boyd <sboyd@...nel.org>,
David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
Svyatoslav Ryhel <clamor95@...il.com>, Dmitry Osipenko <digetx@...il.com>,
Charan Pedumuru <charan.pedumuru@...il.com>,
Svyatoslav Ryhel <clamor95@...il.com>
Cc: devicetree@...r.kernel.org, linux-tegra@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-clk@...r.kernel.org,
dri-devel@...ts.freedesktop.org
Subject:
Re: [PATCH v2 3/4 RESEND] gpu/drm: tegra: dsi: add support for
Tegra20/Tegra30
On Thursday, December 4, 2025 3:17 PM Svyatoslav Ryhel wrote:
> Tegra20 and Tegra30 are fully compatible with existing tegra DSI driver
> apart from clock configuration and PAD calibration which are addressed by
> this patch.
>
> Signed-off-by: Svyatoslav Ryhel <clamor95@...il.com>
> ---
> drivers/gpu/drm/tegra/drm.c | 2 +
> drivers/gpu/drm/tegra/dsi.c | 88 ++++++++++++++++++++++++-------------
> drivers/gpu/drm/tegra/dsi.h | 15 +++++++
> 3 files changed, 74 insertions(+), 31 deletions(-)
>
> diff --git a/drivers/gpu/drm/tegra/drm.c b/drivers/gpu/drm/tegra/drm.c
> index 4596073fe28f..5d64cd57e764 100644
> --- a/drivers/gpu/drm/tegra/drm.c
> +++ b/drivers/gpu/drm/tegra/drm.c
> @@ -1359,10 +1359,12 @@ static SIMPLE_DEV_PM_OPS(host1x_drm_pm_ops, host1x_drm_suspend,
>
> static const struct of_device_id host1x_drm_subdevs[] = {
> { .compatible = "nvidia,tegra20-dc", },
> + { .compatible = "nvidia,tegra20-dsi", },
> { .compatible = "nvidia,tegra20-hdmi", },
> { .compatible = "nvidia,tegra20-gr2d", },
> { .compatible = "nvidia,tegra20-gr3d", },
> { .compatible = "nvidia,tegra30-dc", },
> + { .compatible = "nvidia,tegra30-dsi", },
> { .compatible = "nvidia,tegra30-hdmi", },
> { .compatible = "nvidia,tegra30-gr2d", },
> { .compatible = "nvidia,tegra30-gr3d", },
> diff --git a/drivers/gpu/drm/tegra/dsi.c b/drivers/gpu/drm/tegra/dsi.c
> index 8e80c7efe8b4..d079aa7d2a85 100644
> --- a/drivers/gpu/drm/tegra/dsi.c
> +++ b/drivers/gpu/drm/tegra/dsi.c
> @@ -53,6 +53,10 @@ to_dsi_state(struct drm_connector_state *state)
> return container_of(state, struct tegra_dsi_state, base);
> }
>
> +struct tegra_dsi_config {
> + u32 dsi_version;
Rather than a dsi_version field, we should have something that describes the difference. e.g. 'bool has_multiple_pad_controls' being true for the "V1" hardware.
> +};
> +
> struct tegra_dsi {
> struct host1x_client client;
> struct tegra_output output;
> @@ -82,6 +86,8 @@ struct tegra_dsi {
> /* for ganged-mode support */
> struct tegra_dsi *master;
> struct tegra_dsi *slave;
> +
> + const struct tegra_dsi_config *config;
> };
>
> static inline struct tegra_dsi *
> @@ -663,39 +669,46 @@ static int tegra_dsi_pad_enable(struct tegra_dsi *dsi)
> {
> u32 value;
>
> - value = DSI_PAD_CONTROL_VS1_PULLDN(0) | DSI_PAD_CONTROL_VS1_PDIO(0);
> - tegra_dsi_writel(dsi, value, DSI_PAD_CONTROL_0);
> + if (dsi->config->dsi_version == TEGRA_DSI_V1) {
> + /*
> + * XXX Is this still needed? The module reset is deasserted right
> + * before this function is called.
> + */
> + tegra_dsi_writel(dsi, 0, DSI_PAD_CONTROL_0);
> + tegra_dsi_writel(dsi, 0, DSI_PAD_CONTROL_1);
> + tegra_dsi_writel(dsi, 0, DSI_PAD_CONTROL_2);
> + tegra_dsi_writel(dsi, 0, DSI_PAD_CONTROL_3);
> + tegra_dsi_writel(dsi, 0, DSI_PAD_CONTROL_4);
> +
> + value = DSI_PAD_CONTROL_VS1_PULLDN(0) | DSI_PAD_CONTROL_VS1_PDIO(0);
> + tegra_dsi_writel(dsi, value, DSI_PAD_CONTROL_0);
> +
> + value = DSI_PAD_SLEW_UP(0x7) | DSI_PAD_SLEW_DN(0x7) |
> + DSI_PAD_LP_UP(0x1) | DSI_PAD_LP_DN(0x1) |
> + DSI_PAD_OUT_CLK(0x0);
> + tegra_dsi_writel(dsi, value, DSI_PAD_CONTROL_2);
> +
> + value = DSI_PAD_PREEMP_PD_CLK(0x3) | DSI_PAD_PREEMP_PU_CLK(0x3) |
> + DSI_PAD_PREEMP_PD(0x03) | DSI_PAD_PREEMP_PU(0x3);
> + tegra_dsi_writel(dsi, value, DSI_PAD_CONTROL_3);
> + } else {
> + value = DSI_PAD_CONTROL_LPUPADJ(0x1) | DSI_PAD_CONTROL_LPDNADJ(0x1) |
> + DSI_PAD_CONTROL_PREEMP_EN(0x1) | DSI_PAD_CONTROL_SLEWDNADJ(0x6) |
> + DSI_PAD_CONTROL_SLEWUPADJ(0x6) | DSI_PAD_CONTROL_PDIO(0) |
> + DSI_PAD_CONTROL_PDIO_CLK(0) | DSI_PAD_CONTROL_PULLDN_ENAB(0);
> + tegra_dsi_writel(dsi, value, DSI_PAD_CONTROL_0);
> + }
>
> return 0;
> }
>
> static int tegra_dsi_pad_calibrate(struct tegra_dsi *dsi)
> {
> - u32 value;
> int err;
>
> - /*
> - * XXX Is this still needed? The module reset is deasserted right
> - * before this function is called.
> - */
> - tegra_dsi_writel(dsi, 0, DSI_PAD_CONTROL_0);
> - tegra_dsi_writel(dsi, 0, DSI_PAD_CONTROL_1);
> - tegra_dsi_writel(dsi, 0, DSI_PAD_CONTROL_2);
> - tegra_dsi_writel(dsi, 0, DSI_PAD_CONTROL_3);
> - tegra_dsi_writel(dsi, 0, DSI_PAD_CONTROL_4);
> -
> /* start calibration */
> tegra_dsi_pad_enable(dsi);
>
> - value = DSI_PAD_SLEW_UP(0x7) | DSI_PAD_SLEW_DN(0x7) |
> - DSI_PAD_LP_UP(0x1) | DSI_PAD_LP_DN(0x1) |
> - DSI_PAD_OUT_CLK(0x0);
> - tegra_dsi_writel(dsi, value, DSI_PAD_CONTROL_2);
> -
> - value = DSI_PAD_PREEMP_PD_CLK(0x3) | DSI_PAD_PREEMP_PU_CLK(0x3) |
> - DSI_PAD_PREEMP_PD(0x03) | DSI_PAD_PREEMP_PU(0x3);
> - tegra_dsi_writel(dsi, value, DSI_PAD_CONTROL_3);
> -
> err = tegra_mipi_start_calibration(dsi->mipi);
> if (err < 0)
> return err;
> @@ -1577,6 +1590,7 @@ static int tegra_dsi_probe(struct platform_device *pdev)
> if (!dsi)
> return -ENOMEM;
>
> + dsi->config = of_device_get_match_data(&pdev->dev);
> dsi->output.dev = dsi->dev = &pdev->dev;
> dsi->video_fifo_depth = 1920;
> dsi->host_fifo_depth = 64;
> @@ -1615,7 +1629,7 @@ static int tegra_dsi_probe(struct platform_device *pdev)
> goto remove;
> }
>
> - dsi->clk_lp = devm_clk_get(&pdev->dev, "lp");
> + dsi->clk_lp = devm_clk_get_optional(&pdev->dev, "lp");
> if (IS_ERR(dsi->clk_lp)) {
> err = dev_err_probe(&pdev->dev, PTR_ERR(dsi->clk_lp),
> "cannot get low-power clock\n");
> @@ -1636,10 +1650,12 @@ static int tegra_dsi_probe(struct platform_device *pdev)
> goto remove;
> }
>
> - err = tegra_dsi_setup_clocks(dsi);
> - if (err < 0) {
> - dev_err(&pdev->dev, "cannot setup clocks\n");
> - goto remove;
> + if (dsi->config->dsi_version == TEGRA_DSI_V1) {
And 'has_mux_parent_clk', perhaps? Not a very good name, if you come up with something better feel free to use it.
I checked, and looks like Tegra30 in fact allows DSIA/DSIB to be muxed to either PLL_D or PLL_D2, it is just not modelled in the clock driver. The same applies to all of Tegra114, 124, and 210, but only Tegra114 has it presently modelled as a mux whereas 124 and 210 have a gate. The TRMs for 124 and 210 specify that only PLL_D can be used in the mux bit documentation so the bit is probably dysfunctional on those chips.
The correct solution, hence, I think is to have that config field, and it be false for Tegra20, 124, and 210; and true for Tegra30, and 114. Then implement the mux clock in the Tegra30 clock driver.
However, I would settle for setting it to false for both Tegra20 and Tegra30 and leaving a comment next to the Tegra30 entry describing the situation (the mux clock is not currently modelled).
Cheers,
Mikko
> + err = tegra_dsi_setup_clocks(dsi);
> + if (err < 0) {
> + dev_err(&pdev->dev, "cannot setup clocks\n");
> + goto remove;
> + }
> }
>
> dsi->regs = devm_platform_ioremap_resource(pdev, 0);
> @@ -1703,11 +1719,21 @@ static void tegra_dsi_remove(struct platform_device *pdev)
> tegra_mipi_free(dsi->mipi);
> }
>
> +static const struct tegra_dsi_config tegra20_dsi_config = {
> + .dsi_version = TEGRA_DSI_V0,
> +};
> +
> +static const struct tegra_dsi_config tegra114_dsi_config = {
> + .dsi_version = TEGRA_DSI_V1,
> +};
> +
> static const struct of_device_id tegra_dsi_of_match[] = {
> - { .compatible = "nvidia,tegra210-dsi", },
> - { .compatible = "nvidia,tegra132-dsi", },
> - { .compatible = "nvidia,tegra124-dsi", },
> - { .compatible = "nvidia,tegra114-dsi", },
> + { .compatible = "nvidia,tegra210-dsi", .data = &tegra114_dsi_config },
> + { .compatible = "nvidia,tegra132-dsi", .data = &tegra114_dsi_config },
> + { .compatible = "nvidia,tegra124-dsi", .data = &tegra114_dsi_config },
> + { .compatible = "nvidia,tegra114-dsi", .data = &tegra114_dsi_config },
> + { .compatible = "nvidia,tegra30-dsi", .data = &tegra20_dsi_config },
> + { .compatible = "nvidia,tegra20-dsi", .data = &tegra20_dsi_config },
> { },
> };
> MODULE_DEVICE_TABLE(of, tegra_dsi_of_match);
> diff --git a/drivers/gpu/drm/tegra/dsi.h b/drivers/gpu/drm/tegra/dsi.h
> index f39594e65e97..5049ec7813c7 100644
> --- a/drivers/gpu/drm/tegra/dsi.h
> +++ b/drivers/gpu/drm/tegra/dsi.h
> @@ -95,6 +95,16 @@
> #define DSI_TALLY_LRX(x) (((x) & 0xff) << 8)
> #define DSI_TALLY_HTX(x) (((x) & 0xff) << 0)
> #define DSI_PAD_CONTROL_0 0x4b
> +/* DSI V0 */
> +#define DSI_PAD_CONTROL_PULLDN_ENAB(x) (((x) & 0x1) << 28)
> +#define DSI_PAD_CONTROL_SLEWUPADJ(x) (((x) & 0x7) << 24)
> +#define DSI_PAD_CONTROL_SLEWDNADJ(x) (((x) & 0x7) << 20)
> +#define DSI_PAD_CONTROL_PREEMP_EN(x) (((x) & 0x1) << 19)
> +#define DSI_PAD_CONTROL_PDIO_CLK(x) (((x) & 0x1) << 18)
> +#define DSI_PAD_CONTROL_PDIO(x) (((x) & 0x3) << 16)
> +#define DSI_PAD_CONTROL_LPUPADJ(x) (((x) & 0x3) << 14)
> +#define DSI_PAD_CONTROL_LPDNADJ(x) (((x) & 0x3) << 12)
> +/* DSI V1 */
> #define DSI_PAD_CONTROL_VS1_PDIO(x) (((x) & 0xf) << 0)
> #define DSI_PAD_CONTROL_VS1_PDIO_CLK (1 << 8)
> #define DSI_PAD_CONTROL_VS1_PULLDN(x) (((x) & 0xf) << 16)
> @@ -140,4 +150,9 @@ enum tegra_dsi_format {
> TEGRA_DSI_FORMAT_24P,
> };
>
> +enum tegra_dsi_version {
> + TEGRA_DSI_V0,
> + TEGRA_DSI_V1,
> +};
> +
> #endif
>
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