On Mon, 2019-05-06 at 17:17 +0800, CK Hu wrote:
> Hi, Jitao:
>
> On Tue, 2019-04-16 at 13:42 +0800, Jitao Shi wrote:
> > This patch add mt8183 mipi_tx driver.
> > And also support other chips that use the same binding and driver.
> >
> > Signed-off-by: Jitao Shi <jitao.shi@xxxxxxxxxxxx>
> > ---
> > drivers/gpu/drm/mediatek/Makefile | 1 +
> > drivers/gpu/drm/mediatek/mtk_mipi_tx.c | 2 +
> > drivers/gpu/drm/mediatek/mtk_mipi_tx.h | 1 +
> > drivers/gpu/drm/mediatek/mtk_mt8183_mipi_tx.c | 154 ++++++++++++++++++
> > 4 files changed, 158 insertions(+)
> > create mode 100644 drivers/gpu/drm/mediatek/mtk_mt8183_mipi_tx.c
> >
>
> [snip]
>
> > +
> > +static int mtk_mipi_tx_pll_prepare(struct clk_hw *hw)
> > +{
> > + struct mtk_mipi_tx *mipi_tx = mtk_mipi_tx_from_clk_hw(hw);
> > + unsigned int txdiv, txdiv0;
> > + u64 pcw;
> > + int ret;
> > +
> > + dev_dbg(mipi_tx->dev, "prepare: %u bps\n", mipi_tx->data_rate);
> > +
> > + if (mipi_tx->data_rate >= 2000000000) {
> > + txdiv = 1;
> > + txdiv0 = 0;
> > + } else if (mipi_tx->data_rate >= 1000000000) {
> > + txdiv = 2;
> > + txdiv0 = 1;
> > + } else if (mipi_tx->data_rate >= 500000000) {
> > + txdiv = 4;
> > + txdiv0 = 2;
> > + } else if (mipi_tx->data_rate > 250000000) {
> > + txdiv = 8;
> > + txdiv0 = 3;
> > + } else if (mipi_tx->data_rate >= 125000000) {
> > + txdiv = 16;
> > + txdiv0 = 4;
> > + } else {
> > + return -EINVAL;
> > + }
> > +
> > + ret = clk_prepare_enable(mipi_tx->ref_clk);
> > + if (ret < 0) {
> > + dev_err(mipi_tx->dev,
> > + "can't prepare and enable mipi_tx ref_clk %d\n", ret);
> > + return ret;
> > + }
>
> You enable the parent clock when prepare this clock here, this behavior
> looks strange. I think the flow should be:
>
> 1. Parent clock prepare
> 2. This clock prepare
> 3. Parent clock enable
> 4. This clock enable
>
> Maybe you should implement 'enable callback' so that parent clock would
> be already enabled.
>
> One question is, mipi_tx_pll is used by dsi driver, but I does not see
> dsi prepare_enable() mipi_tx_pll, how does this work?
>
> Regards,
> CK
>
The mipi_tx can be accessed after clk_prepare_enable(mipi_tx->ref_clk);
So place the clk_prepare_enable(mipi_tx->ref_clk) before accessing
mipitx.
mipi_tx_pll is enable by mtk_mipi_tx_power_on() in mtk_mip_tx.c.
clk_prepare_enable(mipi_tx->pll) will enable mipi_tx_pll.
Beset Regards
Jitao
> > +
> > + mtk_mipi_tx_clear_bits(mipi_tx, MIPITX_PLL_CON4, RG_DSI_PLL_IBIAS);
> > +
> > + mtk_mipi_tx_set_bits(mipi_tx, MIPITX_PLL_PWR, AD_DSI_PLL_SDM_PWR_ON);
> > + usleep_range(30, 100);
> > + mtk_mipi_tx_clear_bits(mipi_tx, MIPITX_PLL_PWR, AD_DSI_PLL_SDM_ISO_EN);
> > + pcw = div_u64(((u64)mipi_tx->data_rate * txdiv) << 24, 26000000);
> > + writel(pcw, mipi_tx->regs + MIPITX_PLL_CON0);
> > + mtk_mipi_tx_update_bits(mipi_tx, MIPITX_PLL_CON1, RG_DSI_PLL_POSDIV,
> > + txdiv0 << 8);
> > + usleep_range(1000, 2000);
> > + mtk_mipi_tx_set_bits(mipi_tx, MIPITX_PLL_CON1, RG_DSI_PLL_EN);
> > +
> > + return 0;
> > +}
> > +
> > +static void mtk_mipi_tx_pll_unprepare(struct clk_hw *hw)
> > +{
> > + struct mtk_mipi_tx *mipi_tx = mtk_mipi_tx_from_clk_hw(hw);
> > +
> > + dev_dbg(mipi_tx->dev, "unprepare\n");
> > +
> > + mtk_mipi_tx_clear_bits(mipi_tx, MIPITX_PLL_CON1, RG_DSI_PLL_EN);
> > +
> > + mtk_mipi_tx_set_bits(mipi_tx, MIPITX_PLL_PWR, AD_DSI_PLL_SDM_ISO_EN);
> > + mtk_mipi_tx_clear_bits(mipi_tx, MIPITX_PLL_PWR, AD_DSI_PLL_SDM_PWR_ON);
> > + clk_disable_unprepare(mipi_tx->ref_clk);
> > +}
> > +
>
>
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