Hi, On Tue 27 Oct 20, 19:28, Maxime Ripard wrote: > > Hi, > > On Tue, Oct 27, 2020 at 10:23:26AM +0100, Paul Kocialkowski wrote: > > On Mon 26 Oct 20, 16:38, Maxime Ripard wrote: > > > On Fri, Oct 23, 2020 at 07:45:34PM +0200, Paul Kocialkowski wrote: > > > > The Allwinner A31 D-PHY supports both Rx and Tx modes. While the latter > > > > is already supported and used for MIPI DSI this adds support for the > > > > former, to be used with MIPI CSI-2. > > > > > > > > This implementation is inspired by the Allwinner BSP implementation. > > > > > > Mentionning which BSP you took this from would be helpful > > > > Sure! It's from the Github repo linked from https://linux-sunxi.org/V3s. > > Would you like that I mention this URL explicitly or would it be enough to > > mention "Allwinner's V3s Linux SDK" as they seem to call it? > > Yeah, that would be great > > > > +static int sun6i_dphy_rx_power_on(struct sun6i_dphy *dphy) > > > > +{ > > > > + /* Physical clock rate is actually half of symbol rate with > > > > DDR. */ > > > > + unsigned long mipi_symbol_rate = dphy->config.hs_clk_rate; > > > > + unsigned long dphy_clk_rate; > > > > + unsigned int rx_dly; > > > > + unsigned int lprst_dly; > > > > + u32 value; > > > > + > > > > + dphy_clk_rate = clk_get_rate(dphy->mod_clk); > > > > + if (!dphy_clk_rate) > > > > + return -1; > > > > > > Returning -1 is weird here? > > > > What do you think would be a more appropriate error code to return? > > It looks like some other drivers return -EINVAL when that happens (but many > > don't do the check). > > Yeah, EINVAL at least is better than ENOPERM > > > > > + > > > > + /* Hardcoded timing parameters from the Allwinner BSP. */ > > > > + regmap_write(dphy->regs, SUN6I_DPHY_RX_TIME0_REG, > > > > + SUN6I_DPHY_RX_TIME0_HS_RX_SYNC(255) | > > > > + SUN6I_DPHY_RX_TIME0_HS_RX_CLK_MISS(255) | > > > > + SUN6I_DPHY_RX_TIME0_LP_RX(255)); > > > > + > > > > + /* > > > > + * Formula from the Allwinner BSP, with hardcoded coefficients > > > > + * (probably internal divider/multiplier). > > > > + */ > > > > + rx_dly = 8 * (unsigned int)(dphy_clk_rate / (mipi_symbol_rate / > > > > 8)); > > > > + > > > > + /* > > > > + * The Allwinner BSP has an alternative formula for > > > > LP_RX_ULPS_WP: > > > > + * lp_ulps_wp_cnt = lp_ulps_wp_ms * lp_clk / 1000 > > > > + * but does not use it and hardcodes 255 instead. > > > > + */ > > > > + regmap_write(dphy->regs, SUN6I_DPHY_RX_TIME1_REG, > > > > + SUN6I_DPHY_RX_TIME1_RX_DLY(rx_dly) | > > > > + SUN6I_DPHY_RX_TIME1_LP_RX_ULPS_WP(255)); > > > > + > > > > + /* HS_RX_ANA0 value is hardcoded in the Allwinner BSP. */ > > > > + regmap_write(dphy->regs, SUN6I_DPHY_RX_TIME2_REG, > > > > + SUN6I_DPHY_RX_TIME2_HS_RX_ANA0(4)); > > > > + > > > > + /* > > > > + * Formula from the Allwinner BSP, with hardcoded coefficients > > > > + * (probably internal divider/multiplier). > > > > + */ > > > > + lprst_dly = 4 * (unsigned int)(dphy_clk_rate / > > > > (mipi_symbol_rate / 2)); > > > > + > > > > + regmap_write(dphy->regs, SUN6I_DPHY_RX_TIME3_REG, > > > > + SUN6I_DPHY_RX_TIME3_LPRST_DLY(lprst_dly)); > > > > + > > > > + /* Analog parameters are hardcoded in the Allwinner BSP. */ > > > > + regmap_write(dphy->regs, SUN6I_DPHY_ANA0_REG, > > > > + SUN6I_DPHY_ANA0_REG_PWS | > > > > + SUN6I_DPHY_ANA0_REG_SLV(7) | > > > > + SUN6I_DPHY_ANA0_REG_SFB(2)); > > > > + > > > > + regmap_write(dphy->regs, SUN6I_DPHY_ANA1_REG, > > > > + SUN6I_DPHY_ANA1_REG_SVTT(4)); > > > > + > > > > + regmap_write(dphy->regs, SUN6I_DPHY_ANA4_REG, > > > > + SUN6I_DPHY_ANA4_REG_DMPLVC | > > > > + SUN6I_DPHY_ANA4_REG_DMPLVD(1)); > > > > + > > > > + regmap_write(dphy->regs, SUN6I_DPHY_ANA2_REG, > > > > + SUN6I_DPHY_ANA2_REG_ENIB); > > > > + > > > > + regmap_write(dphy->regs, SUN6I_DPHY_ANA3_REG, > > > > + SUN6I_DPHY_ANA3_EN_LDOR | > > > > + SUN6I_DPHY_ANA3_EN_LDOC | > > > > + SUN6I_DPHY_ANA3_EN_LDOD); > > > > + > > > > + /* > > > > + * Delay comes from the Allwinner BSP, likely for internal > > > > regulator > > > > + * ramp-up. > > > > + */ > > > > + udelay(3); > > > > + > > > > + value = SUN6I_DPHY_RX_CTL_EN_DBC | > > > > SUN6I_DPHY_RX_CTL_RX_CLK_FORCE; > > > > + > > > > + /* > > > > + * Rx data lane force-enable bits are used as regular RX enable > > > > by the > > > > + * Allwinner BSP. > > > > + */ > > > > + if (dphy->config.lanes >= 1) > > > > + value |= SUN6I_DPHY_RX_CTL_RX_D0_FORCE; > > > > + if (dphy->config.lanes >= 2) > > > > + value |= SUN6I_DPHY_RX_CTL_RX_D1_FORCE; > > > > + if (dphy->config.lanes >= 3) > > > > + value |= SUN6I_DPHY_RX_CTL_RX_D2_FORCE; > > > > + if (dphy->config.lanes == 4) > > > > + value |= SUN6I_DPHY_RX_CTL_RX_D3_FORCE; > > > > + > > > > + regmap_write(dphy->regs, SUN6I_DPHY_RX_CTL_REG, value); > > > > + > > > > + regmap_write(dphy->regs, SUN6I_DPHY_GCTL_REG, > > > > + SUN6I_DPHY_GCTL_LANE_NUM(dphy->config.lanes) | > > > > + SUN6I_DPHY_GCTL_EN); > > > > + > > > > + return 0; > > > > +} > > > > + > > > > +static int sun6i_dphy_power_on(struct phy *phy) > > > > +{ > > > > + struct sun6i_dphy *dphy = phy_get_drvdata(phy); > > > > + > > > > + switch (dphy->submode) { > > > > + case PHY_MIPI_DPHY_SUBMODE_TX: > > > > + return sun6i_dphy_tx_power_on(dphy); > > > > + case PHY_MIPI_DPHY_SUBMODE_RX: > > > > + return sun6i_dphy_rx_power_on(dphy); > > > > + default: > > > > + return -EINVAL; > > > > + } > > > > +} > > > > + > > > > > > Can one call power_on before set_mode? > > > > I didn't find anything indicating this is illegal. What would happen here is > > that the D-PHY would be configured to PHY_MIPI_DPHY_SUBMODE_TX (submode == > > 0) > > at power-on if set_mode is not called before. > > > > I think it's fair to expect that it's too late to change the mode once the > > PHY > > was powered on. Maybe we should return -EBUSY on set_mode when power on was > > already requested? > > Or maybe we can just clarify it in the framework/function documentation
Agreed, I'll add a patch in that direction. I would also be tempted to check on phy->power_count to return -EBUSY in phy_set_mode_ext so that the behavior is enforced. What do you think? Cheers, Paul -- Paul Kocialkowski, Bootlin Embedded Linux and kernel engineering https://bootlin.com
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