Re: [PATCH v3 4/7] phy: cdns-dphy: Add Rx support

From: Pratyush Yadav
Date: Wed Aug 11 2021 - 13:34:00 EST

On 06/08/21 04:45PM, Vinod Koul wrote:
> On 25-06-21, 00:11, Pratyush Yadav wrote:
> > The Cadence DPHY can be used to receive image data over the CSI-2
> > protocol. Add support for Rx mode. The programming sequence differs from
> > the Tx mode so it is added as a separate set of hooks to isolate the two
> > paths.
> >
> > The PHY is in Tx mode by default and it needs to be set in Rx mode by
> > setting the submode to PHY_MIPI_DPHY_SUBMODE_RX in the set_mode()
> > callback.
> >
> > Signed-off-by: Pratyush Yadav <p.yadav@xxxxxx>
> >
> > ---
> >
> > Changes in v3:
> > - Use a table to select the band.
> > - Use a table to poll the data lane ready bits.
> > - Multiply the DPHY HS clock rate by 2 to get the bit rate since the
> > clock is DDR.
> >
> > drivers/phy/cadence/cdns-dphy.c | 174 ++++++++++++++++++++++++++++++++
> > 1 file changed, 174 insertions(+)
> >
> > diff --git a/drivers/phy/cadence/cdns-dphy.c b/drivers/phy/cadence/cdns-dphy.c
> > index 7d5f7b333893..7534ec957dc5 100644
> > --- a/drivers/phy/cadence/cdns-dphy.c
> > +++ b/drivers/phy/cadence/cdns-dphy.c
> > @@ -1,11 +1,14 @@
> > // SPDX-License-Identifier: GPL-2.0+
> > /*
> > * Copyright: 2017-2018 Cadence Design Systems, Inc.
> > + * Copyright (C) 2021 Texas Instruments Incorporated - https://www.ti.com/
> > */
> >
> > #include <linux/bitops.h>
> > +#include <linux/bitfield.h>
> > #include <linux/clk.h>
> > #include <linux/io.h>
> > +#include <linux/iopoll.h>
> > #include <linux/module.h>
> > #include <linux/of_address.h>
> > #include <linux/of_device.h>
> > @@ -25,10 +28,14 @@
> > #define DPHY_PMA_RCLK(reg) (0x600 + (reg))
> > #define DPHY_PMA_RDATA(lane, reg) (0x700 + ((lane) * 0x100) + (reg))
> > #define DPHY_PCS(reg) (0xb00 + (reg))
> > +#define DPHY_ISO(reg) (0xc00 + (reg))
> >
> > #define DPHY_CMN_SSM DPHY_PMA_CMN(0x20)
> > #define DPHY_CMN_SSM_EN BIT(0)
> > +#define DPHY_CMN_RX_BANDGAP_TIMER_MASK GENMASK(8, 1)
> > #define DPHY_CMN_TX_MODE_EN BIT(9)
> > +#define DPHY_CMN_RX_MODE_EN BIT(10)
> > +#define DPHY_CMN_RX_BANDGAP_TIMER 0x14
> >
> > #define DPHY_CMN_PWM DPHY_PMA_CMN(0x40)
> > #define DPHY_CMN_PWM_DIV(x) ((x) << 20)
> > @@ -45,10 +52,27 @@
> > #define DPHY_CMN_OPDIV_FROM_REG BIT(6)
> > #define DPHY_CMN_OPDIV(x) ((x) << 7)
> >
> > +#define DPHY_BAND_CFG DPHY_PCS(0x0)
> > +#define DPHY_BAND_CFG_LEFT_BAND GENMASK(4, 0)
> > +#define DPHY_BAND_CFG_RIGHT_BAND GENMASK(9, 5)
> > +
> > #define DPHY_PSM_CFG DPHY_PCS(0x4)
> > #define DPHY_PSM_CFG_FROM_REG BIT(0)
> > #define DPHY_PSM_CLK_DIV(x) ((x) << 1)
> >
> > +#define DPHY_POWER_ISLAND_EN_DATA DPHY_PCS(0x8)
> > +#define DPHY_POWER_ISLAND_EN_DATA_VAL 0xaaaaaaaa
> > +#define DPHY_POWER_ISLAND_EN_CLK DPHY_PCS(0xc)
> > +#define DPHY_POWER_ISLAND_EN_CLK_VAL 0xaa
> > +
> > +#define DPHY_ISO_CL_CTRL_L DPHY_ISO(0x10)
> > +#define DPHY_ISO_DL_CTRL_L0 DPHY_ISO(0x14)
> > +#define DPHY_ISO_DL_CTRL_L1 DPHY_ISO(0x20)
> > +#define DPHY_ISO_DL_CTRL_L2 DPHY_ISO(0x30)
> > +#define DPHY_ISO_DL_CTRL_L3 DPHY_ISO(0x3c)
> > +#define DPHY_ISO_LANE_READY_BIT 0
> > +#define DPHY_ISO_LANE_READY_TIMEOUT_MS 100UL
> > +
> > #define DSI_HBP_FRAME_OVERHEAD 12
> > #define DSI_HSA_FRAME_OVERHEAD 14
> > #define DSI_HFP_FRAME_OVERHEAD 6
> > @@ -57,6 +81,9 @@
> > #define DSI_NULL_FRAME_OVERHEAD 6
> > #define DSI_EOT_PKT_SIZE 4
> >
> > +#define DPHY_LANES_MIN 1
> > +#define DPHY_LANES_MAX 4
> > +
> > struct cdns_dphy_cfg {
> > u8 pll_ipdiv;
> > u8 pll_opdiv;
> > @@ -103,6 +130,22 @@ struct cdns_dphy_driver_data {
> > const struct cdns_dphy_ops *rx;
> > };
> >
> > +struct cdns_dphy_rx_band {
> > + unsigned int min_rate;
> > + unsigned int max_rate;
> > +};
> > +
> > +/* Order of bands is important since the index is the band number. */
> > +struct cdns_dphy_rx_band bands[] = {
> > + {80, 100}, {100, 120}, {120, 160}, {160, 200}, {200, 240},
> > + {240, 280}, {280, 320}, {320, 360}, {360, 400}, {400, 480},
> > + {480, 560}, {560, 640}, {640, 720}, {720, 800}, {800, 880},
> > + {880, 1040}, {1040, 1200}, {1200, 1350}, {1350, 1500}, {1500, 1750},
> > + {1750, 2000}, {2000, 2250}, {2250, 2500}
> > +};
> > +
> > +int num_bands = ARRAY_SIZE(bands);
> > +
> > static int cdns_dsi_get_dphy_pll_cfg(struct cdns_dphy *dphy,
> > struct cdns_dphy_cfg *cfg,
> > struct phy_configure_opts_mipi_dphy *opts,
> > @@ -312,6 +355,135 @@ static const struct cdns_dphy_ops tx_ref_dphy_ops = {
> > .set_psm_div = cdns_dphy_ref_set_psm_div,
> > };
> >
> > +static int cdns_dphy_rx_power_on(struct cdns_dphy *dphy)
> > +{
> > + /* Start RX state machine. */
> > + writel(DPHY_CMN_SSM_EN | DPHY_CMN_RX_MODE_EN |
> > + FIELD_PREP(DPHY_CMN_RX_BANDGAP_TIMER_MASK,
> > + DPHY_CMN_RX_BANDGAP_TIMER),
> > + dphy->regs + DPHY_CMN_SSM);
> > +
> > + return 0;
> > +}
> > +
> > +static int cdns_dphy_rx_power_off(struct cdns_dphy *dphy)
> > +{
> > + writel(0, dphy->regs + DPHY_CMN_SSM);
> > +
> > + return 0;
> > +}
> > +
> > +static int cdns_dphy_rx_get_band_ctrl(unsigned long hs_clk_rate)
> > +{
> > + unsigned int rate;
> > + int i;
> > +
> > + rate = hs_clk_rate / 1000000UL;
> > + /* Since CSI-2 clock is DDR, the bit rate is twice the clock rate. */
> > + rate *= 2;
> > +
> > + if (rate < bands[0].min_rate || rate >= bands[num_bands - 1].max_rate)
> > + return -EOPNOTSUPP;
> > +
> > + for (i = 0; i < num_bands; i++) {
> > + if (rate >= bands[i].min_rate && rate < bands[i].max_rate)
> > + return i;
> > + }
> > +
> > + /* Unreachable. */
> > + WARN(1, "Reached unreachable code.");
> > + return -EINVAL;
> > +}
> > +
> > +static int cdns_dphy_rx_wait_for_bit(void __iomem *addr, unsigned int bit)
> > +{
> > + u32 val;
> > +
> > + return readl_relaxed_poll_timeout(addr, val, val & BIT(bit), 10,
> > + DPHY_ISO_LANE_READY_TIMEOUT_MS * 1000);
>
> this looks wrong, val is not initialized, so what/when is condition to
> be met..?

The readl_relaxed_poll_timeout() macro puts the value returned by
readl() into val. That value is then used for testing the condition. See
read_poll_timeout() in iopoll.h to see what the macro eventually expands
to.

> --
> ~Vinod

--
Regards,
Pratyush Yadav
Texas Instruments Inc.