Re: [PATCH v9 09/10] drm/mediatek: update DSI sub driver flow for sending commands to panel

Daniel Kurtz
2016-11-18T03:21:44Z

Hi YT,

Sorry for the very late review.

My biggest problem with this patch is it describes itself as adding
support for a new use case "DSI -> panel", but makes many changes to
the existing working flow "DSI -> bridge -> panel".
If these changes are really needed, or improve the existing flow, I'd
expect to see those changes added first in a preparatory patch,
followed by a second smaller, simpler
patch that adds any additional functionality required to enable the new flow.

See detailed comments inline.

On Fri, Nov 11, 2016 at 7:55 PM, YT Shen <yt.shen@mediatek.com> wrote:
>
> This patch update enable/disable flow of DSI module and MIPI TX module.
> Original flow works on there is a bridge chip: DSI -> bridge -> panel.
> In this case: DSI -> panel, the DSI sub driver flow should be updated.
> We need to initialize DSI first so that we can send commands to panel.
>
> Signed-off-by: shaoming chen <shaoming.chen@mediatek.com>
> Signed-off-by: YT Shen <yt.shen@mediatek.com>
> ---
> drivers/gpu/drm/mediatek/mtk_dsi.c | 110 ++++++++++++++++++++++++++-------
> drivers/gpu/drm/mediatek/mtk_mipi_tx.c | 32 +++++-----
> 2 files changed, 103 insertions(+), 39 deletions(-)
>
> diff --git a/drivers/gpu/drm/mediatek/mtk_dsi.c b/drivers/gpu/drm/mediatek/mtk_dsi.c
> index 860b84f..12a1206 100644
> --- a/drivers/gpu/drm/mediatek/mtk_dsi.c
> +++ b/drivers/gpu/drm/mediatek/mtk_dsi.c
> @@ -94,6 +94,8 @@
> #define DSI_RACK 0x84
> #define RACK BIT(0)
>
> +#define DSI_MEM_CONTI 0x90
> +
> #define DSI_PHY_LCCON 0x104
> #define LC_HS_TX_EN BIT(0)
> #define LC_ULPM_EN BIT(1)
> @@ -126,6 +128,10 @@
> #define CLK_HS_POST (0xff << 8)
> #define CLK_HS_EXIT (0xff << 16)
>
> +#define DSI_VM_CMD_CON 0x130
> +#define VM_CMD_EN BIT(0)
> +#define TS_VFP_EN BIT(5)
> +
> #define DSI_CMDQ0 0x180
> #define CONFIG (0xff << 0)
> #define SHORT_PACKET 0
> @@ -219,12 +225,12 @@ static void mtk_dsi_phy_timconfig(struct mtk_dsi *dsi)
> writel(timcon3, dsi->regs + DSI_PHY_TIMECON3);
> }
>
> -static void mtk_dsi_enable(struct mtk_dsi *dsi)
> +static void mtk_dsi_engine_enable(struct mtk_dsi *dsi)

I don't think we need to change these names.

> {
> mtk_dsi_mask(dsi, DSI_CON_CTRL, DSI_EN, DSI_EN);
> }
>
> -static void mtk_dsi_disable(struct mtk_dsi *dsi)
> +static void mtk_dsi_engine_disable(struct mtk_dsi *dsi)
> {
> mtk_dsi_mask(dsi, DSI_CON_CTRL, DSI_EN, 0);
> }
> @@ -249,7 +255,9 @@ static int mtk_dsi_poweron(struct mtk_dsi *dsi)
> * mipi_ratio is mipi clk coefficient for balance the pixel clk in mipi.
> * we set mipi_ratio is 1.05.
> */
> - dsi->data_rate = dsi->vm.pixelclock * 3 * 21 / (1 * 1000 * 10);
> + dsi->data_rate = dsi->vm.pixelclock * 12 * 21;
> + dsi->data_rate /= (dsi->lanes * 1000 * 10);
> + dev_info(dev, "set mipitx's data rate: %dMHz\n", dsi->data_rate);

I don't think we want to spam the log like this. Use dev_dbg.... or
use the DRM_() messaging like elsewhere in this driver?

>
> ret = clk_set_rate(dsi->hs_clk, dsi->data_rate * 1000000);
> if (ret < 0) {
> @@ -271,7 +279,7 @@ static int mtk_dsi_poweron(struct mtk_dsi *dsi)
> goto err_disable_engine_clk;
> }
>
> - mtk_dsi_enable(dsi);
> + mtk_dsi_engine_enable(dsi);
> mtk_dsi_reset_engine(dsi);
> mtk_dsi_phy_timconfig(dsi);
>
> @@ -289,7 +297,7 @@ static int mtk_dsi_poweron(struct mtk_dsi *dsi)
> static void mtk_dsi_clk_ulp_mode_enter(struct mtk_dsi *dsi)
> {
> mtk_dsi_mask(dsi, DSI_PHY_LCCON, LC_HS_TX_EN, 0);
> - mtk_dsi_mask(dsi, DSI_PHY_LCCON, LC_ULPM_EN, 0);
> + mtk_dsi_mask(dsi, DSI_PHY_LCCON, LC_ULPM_EN, LC_ULPM_EN);

What does this change do?
It looks like a pure bug fix (ie, previoulsy we were'nt actually
enabling ULP MODE before).
If so, can you please move it to a separate preliminary patch.

> }
>
> static void mtk_dsi_clk_ulp_mode_leave(struct mtk_dsi *dsi)
> @@ -302,7 +310,7 @@ static void mtk_dsi_clk_ulp_mode_leave(struct mtk_dsi *dsi)
> static void mtk_dsi_lane0_ulp_mode_enter(struct mtk_dsi *dsi)
> {
> mtk_dsi_mask(dsi, DSI_PHY_LD0CON, LD0_HS_TX_EN, 0);
> - mtk_dsi_mask(dsi, DSI_PHY_LD0CON, LD0_ULPM_EN, 0);
> + mtk_dsi_mask(dsi, DSI_PHY_LD0CON, LD0_ULPM_EN, LD0_ULPM_EN);

Same here.

> }
>
> static void mtk_dsi_lane0_ulp_mode_leave(struct mtk_dsi *dsi)
> @@ -338,11 +346,21 @@ static void mtk_dsi_set_mode(struct mtk_dsi *dsi)
> if ((dsi->mode_flags & MIPI_DSI_MODE_VIDEO_BURST) &&
> !(dsi->mode_flags & MIPI_DSI_MODE_VIDEO_SYNC_PULSE))
> vid_mode = BURST_MODE;
> + else
> + vid_mode = SYNC_EVENT_MODE;

So, when do we use SYNC_PULSE_MODE (set just before the 'if')?

> }
>
> writel(vid_mode, dsi->regs + DSI_MODE_CTRL);
> }
>
> +static void mtk_dsi_set_vm_cmd(struct mtk_dsi *dsi)
> +{
> + writel(0x3c, dsi->regs + DSI_MEM_CONTI);

Please use #defined constants, especially if this register is a bit field.
Also, this looks like new behavior which doesn't seem related to
changing the enable order.
If this is a general fix, please use a separate patch.

> +
> + mtk_dsi_mask(dsi, DSI_VM_CMD_CON, VM_CMD_EN, VM_CMD_EN);
> + mtk_dsi_mask(dsi, DSI_VM_CMD_CON, TS_VFP_EN, TS_VFP_EN);
> +}
> +
> static void mtk_dsi_ps_control_vact(struct mtk_dsi *dsi)
> {
> struct videomode *vm = &dsi->vm;
> @@ -399,6 +417,9 @@ static void mtk_dsi_rxtx_control(struct mtk_dsi *dsi)
> break;
> }
>
> + tmp_reg |= (dsi->mode_flags & MIPI_DSI_CLOCK_NON_CONTINUOUS) << 6;
> + tmp_reg |= (dsi->mode_flags & MIPI_DSI_MODE_EOT_PACKET) >> 3;
> +

ditto

> writel(tmp_reg, dsi->regs + DSI_TXRX_CTRL);
> }
>
> @@ -477,6 +498,16 @@ static void mtk_dsi_start(struct mtk_dsi *dsi)
> writel(1, dsi->regs + DSI_START);
> }
>
> +static void mtk_dsi_stop(struct mtk_dsi *dsi)
> +{
> + writel(0, dsi->regs + DSI_START);
> +}
> +
> +static void mtk_dsi_set_cmd_mode(struct mtk_dsi *dsi)
> +{
> + writel(CMD_MODE, dsi->regs + DSI_MODE_CTRL);
> +}
> +
> static void mtk_dsi_set_interrupt_enable(struct mtk_dsi *dsi)
> {
> u32 inten = LPRX_RD_RDY_INT_FLAG | CMD_DONE_INT_FLAG | VM_DONE_INT_FLAG;
> @@ -506,7 +537,7 @@ static s32 mtk_dsi_wait_for_irq_done(struct mtk_dsi *dsi, u32 irq_flag,
> if (ret == 0) {
> dev_info(dsi->dev, "Wait DSI IRQ(0x%08x) Timeout\n", irq_flag);
>
> - mtk_dsi_enable(dsi);
> + mtk_dsi_engine_enable(dsi);
> mtk_dsi_reset_engine(dsi);
> }
>
> @@ -535,6 +566,17 @@ static irqreturn_t mtk_dsi_irq(int irq, void *dev_id)
> return IRQ_HANDLED;
> }
>
> +static s32 mtk_dsi_switch_to_cmd_mode(struct mtk_dsi *dsi, u8 irq_flag, u32 t)
> +{
> + mtk_dsi_irq_data_clear(dsi, irq_flag);
> + mtk_dsi_set_cmd_mode(dsi);
> +
> + if (!mtk_dsi_wait_for_irq_done(dsi, irq_flag, t))
> + return -1;

No, use a real linux errno, and return an int, and print an error
message if this is unexpected.

> + else
> + return 0;
> +}
> +
> static void mtk_dsi_poweroff(struct mtk_dsi *dsi)
> {
> if (WARN_ON(dsi->refcount == 0))
> @@ -543,11 +585,6 @@ static void mtk_dsi_poweroff(struct mtk_dsi *dsi)
> if (--dsi->refcount != 0)
> return;
>
> - mtk_dsi_lane0_ulp_mode_enter(dsi);
> - mtk_dsi_clk_ulp_mode_enter(dsi);
> -
> - mtk_dsi_disable(dsi);
> -
> clk_disable_unprepare(dsi->engine_clk);
> clk_disable_unprepare(dsi->digital_clk);
>
> @@ -561,35 +598,45 @@ static void mtk_output_dsi_enable(struct mtk_dsi *dsi)
> if (dsi->enabled)
> return;
>
> - if (dsi->panel) {
> - if (drm_panel_prepare(dsi->panel)) {
> - DRM_ERROR("failed to setup the panel\n");
> - return;
> - }
> - }
> -
> ret = mtk_dsi_poweron(dsi);
> if (ret < 0) {
> DRM_ERROR("failed to power on dsi\n");
> return;
> }
>
> + usleep_range(20000, 21000);
> +

Why are you adding a 20 ms delay where there was none before?

> mtk_dsi_rxtx_control(dsi);
> + mtk_dsi_phy_timconfig(dsi);
> + mtk_dsi_ps_control_vact(dsi);
> + mtk_dsi_set_vm_cmd(dsi);
> + mtk_dsi_config_vdo_timing(dsi);
> + mtk_dsi_set_interrupt_enable(dsi);
>
> + mtk_dsi_engine_enable(dsi);
> mtk_dsi_clk_ulp_mode_leave(dsi);
> mtk_dsi_lane0_ulp_mode_leave(dsi);
> mtk_dsi_clk_hs_mode(dsi, 0);
> - mtk_dsi_set_mode(dsi);
>
> - mtk_dsi_ps_control_vact(dsi);
> - mtk_dsi_config_vdo_timing(dsi);
> - mtk_dsi_set_interrupt_enable(dsi);
> + if (dsi->panel) {
> + if (drm_panel_prepare(dsi->panel)) {
> + DRM_ERROR("failed to prepare the panel\n");
> + return;
> + }
> + }
>
> mtk_dsi_set_mode(dsi);
> mtk_dsi_clk_hs_mode(dsi, 1);
>
> mtk_dsi_start(dsi);
>
> + if (dsi->panel) {
> + if (drm_panel_enable(dsi->panel)) {
> + DRM_ERROR("failed to enable the panel\n");

In case of error, you must undo everything done to this point. At least:
(1) unprepare the panel
(2) stop dsi
(3) poweroff dsi

> + return;
> + }
> + }
> +
> dsi->enabled = true;
> }
>
> @@ -605,6 +652,21 @@ static void mtk_output_dsi_disable(struct mtk_dsi *dsi)
> }
> }
>
> + mtk_dsi_stop(dsi);
> + mtk_dsi_switch_to_cmd_mode(dsi, VM_DONE_INT_FLAG, 500);

This function can return an error, so please check it. Although,
there probably isn't much you can do here about it.

> +
> + if (dsi->panel) {
> + if (drm_panel_unprepare(dsi->panel)) {
> + DRM_ERROR("failed to unprepare the panel\n");
> + return;

I think you should probably just ignore this error and continue
disabling dsi, since it isn't really recoverable and you can't roll
back and re-enable dsi.

> + }
> + }
> +
> + mtk_dsi_reset_engine(dsi);
> + mtk_dsi_lane0_ulp_mode_enter(dsi);
> + mtk_dsi_clk_ulp_mode_enter(dsi);
> + mtk_dsi_engine_disable(dsi);
> +
> mtk_dsi_poweroff(dsi);
>
> dsi->enabled = false;
> @@ -845,7 +907,7 @@ static void mtk_dsi_wait_for_idle(struct mtk_dsi *dsi)
> if (timeout_ms == 0) {
> dev_info(dsi->dev, "polling dsi wait not busy timeout!\n");
>
> - mtk_dsi_enable(dsi);
> + mtk_dsi_engine_enable(dsi);
> mtk_dsi_reset_engine(dsi);
> }
> }
> diff --git a/drivers/gpu/drm/mediatek/mtk_mipi_tx.c b/drivers/gpu/drm/mediatek/mtk_mipi_tx.c
> index 108d31a..34e95c6 100644
> --- a/drivers/gpu/drm/mediatek/mtk_mipi_tx.c
> +++ b/drivers/gpu/drm/mediatek/mtk_mipi_tx.c
> @@ -177,7 +177,9 @@ static int mtk_mipi_tx_pll_prepare(struct clk_hw *hw)
>
> dev_dbg(mipi_tx->dev, "prepare: %u Hz\n", mipi_tx->data_rate);
>
> - if (mipi_tx->data_rate >= 500000000) {
> + if (mipi_tx->data_rate > 1250000000) {
> + return -EINVAL;
> + } else if (mipi_tx->data_rate >= 500000000) {

Capping the max data rate looks like an unrelated fix.

> txdiv = 1;
> txdiv0 = 0;
> txdiv1 = 0;
> @@ -201,6 +203,10 @@ static int mtk_mipi_tx_pll_prepare(struct clk_hw *hw)
> return -EINVAL;
> }
>
> + mtk_mipi_tx_update_bits(mipi_tx, MIPITX_DSI_TOP_CON,
> + RG_DSI_LNT_IMP_CAL_CODE | RG_DSI_LNT_HS_BIAS_EN,
> + (8 << 4) | RG_DSI_LNT_HS_BIAS_EN);
> +
> mtk_mipi_tx_update_bits(mipi_tx, MIPITX_DSI_BG_CON,
> RG_DSI_VOUT_MSK |
> RG_DSI_BG_CKEN | RG_DSI_BG_CORE_EN,
> @@ -210,24 +216,18 @@ static int mtk_mipi_tx_pll_prepare(struct clk_hw *hw)
>
> usleep_range(30, 100);
>
> - mtk_mipi_tx_update_bits(mipi_tx, MIPITX_DSI_TOP_CON,
> - RG_DSI_LNT_IMP_CAL_CODE | RG_DSI_LNT_HS_BIAS_EN,
> - (8 << 4) | RG_DSI_LNT_HS_BIAS_EN);
> -
> - mtk_mipi_tx_set_bits(mipi_tx, MIPITX_DSI_CON,
> - RG_DSI_CKG_LDOOUT_EN | RG_DSI_LDOCORE_EN);
> + mtk_mipi_tx_update_bits(mipi_tx, MIPITX_DSI_CON,
> + RG_DSI_CKG_LDOOUT_EN | RG_DSI_LDOCORE_EN,
> + RG_DSI_CKG_LDOOUT_EN | RG_DSI_LDOCORE_EN);

Changing from set_bits to update_bits does not do anything. Please
leave this alone.

>
> mtk_mipi_tx_update_bits(mipi_tx, MIPITX_DSI_PLL_PWR,
> RG_DSI_MPPLL_SDM_PWR_ON |
> RG_DSI_MPPLL_SDM_ISO_EN,
> RG_DSI_MPPLL_SDM_PWR_ON);
>
> - mtk_mipi_tx_clear_bits(mipi_tx, MIPITX_DSI_PLL_CON0,
> - RG_DSI_MPPLL_PLL_EN);
> -

Why don't you need to disable the PLL first now?

> mtk_mipi_tx_update_bits(mipi_tx, MIPITX_DSI_PLL_CON0,
> - RG_DSI_MPPLL_TXDIV0 | RG_DSI_MPPLL_TXDIV1 |
> - RG_DSI_MPPLL_PREDIV,
> + RG_DSI_MPPLL_PREDIV | RG_DSI_MPPLL_TXDIV0 |
> + RG_DSI_MPPLL_TXDIV1 | RG_DSI_MPPLL_POSDIV,
> (txdiv0 << 3) | (txdiv1 << 5));

If I read this right, the only thing you are changing is clearing
"RG_DSI_MPPLL_POSDIV".
This would be more clear if you kept the field order: TXDIV0, TXDIV1, PREDIV.

And why are you making this change in this patch?

>
> /*
> @@ -242,10 +242,12 @@ static int mtk_mipi_tx_pll_prepare(struct clk_hw *hw)
> 26000000);
> writel(pcw, mipi_tx->regs + MIPITX_DSI_PLL_CON2);
>
> - mtk_mipi_tx_set_bits(mipi_tx, MIPITX_DSI_PLL_CON1,
> - RG_DSI_MPPLL_SDM_FRA_EN);
> + mtk_mipi_tx_update_bits(mipi_tx, MIPITX_DSI_PLL_CON1,
> + RG_DSI_MPPLL_SDM_FRA_EN,
> + RG_DSI_MPPLL_SDM_FRA_EN);

AFAICT, this change does not do anything but make the code more confusing.

>
> - mtk_mipi_tx_set_bits(mipi_tx, MIPITX_DSI_PLL_CON0, RG_DSI_MPPLL_PLL_EN);
> + mtk_mipi_tx_update_bits(mipi_tx, MIPITX_DSI_PLL_CON0,
> + RG_DSI_MPPLL_PLL_EN, RG_DSI_MPPLL_PLL_EN);

AFAICT, this change does not do anything but make the code more confusing.

>
> usleep_range(20, 100);
>
> --
> 1.9.1
>