Messages in this thread | | | Date | Thu, 20 Oct 2022 12:32:13 +0300 | Subject | Re: [PATCH v2 15/15] phy: qcom-qmp-pcie: add support for sc8280xp 4-lane PHYs | From | Dmitry Baryshkov <> |
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On 20/10/2022 09:43, Johan Hovold wrote: > On Thu, Oct 20, 2022 at 06:43:47AM +0300, Dmitry Baryshkov wrote: >> On 19/10/2022 14:35, Johan Hovold wrote: >>> The PCIe2 and PCIe3 controllers and PHYs on SC8280XP can be used in >>> 4-lane mode or as separate controllers and PHYs in 2-lane mode (e.g. as >>> PCIe2A and PCIe2B). >>> >>> Add support for fetching the 4-lane configuration from the TCSR and >>> programming the lane registers of the second port when in 4-lane mode. >>> >>> Signed-off-by: Johan Hovold <johan+linaro@kernel.org> >>> --- >>> drivers/phy/qualcomm/Kconfig | 1 + >>> drivers/phy/qualcomm/phy-qcom-qmp-pcie.c | 118 +++++++++++++++++++++++ >>> 2 files changed, 119 insertions(+) >>> >>> diff --git a/drivers/phy/qualcomm/Kconfig b/drivers/phy/qualcomm/Kconfig >>> index 5c98850f5a36..eb9ddc685b38 100644 >>> --- a/drivers/phy/qualcomm/Kconfig >>> +++ b/drivers/phy/qualcomm/Kconfig >>> @@ -54,6 +54,7 @@ config PHY_QCOM_QMP >>> tristate "Qualcomm QMP PHY Driver" >>> depends on OF && COMMON_CLK && (ARCH_QCOM || COMPILE_TEST) >>> select GENERIC_PHY >>> + select MFD_SYSCON >>> help >>> Enable this to support the QMP PHY transceiver that is used >>> with controllers such as PCIe, UFS, and USB on Qualcomm chips. >>> diff --git a/drivers/phy/qualcomm/phy-qcom-qmp-pcie.c b/drivers/phy/qualcomm/phy-qcom-qmp-pcie.c >>> index ea5228bd9ecc..e5bce4810bb5 100644 >>> --- a/drivers/phy/qualcomm/phy-qcom-qmp-pcie.c >>> +++ b/drivers/phy/qualcomm/phy-qcom-qmp-pcie.c >>> @@ -10,6 +10,7 @@ >>> #include <linux/io.h> >>> #include <linux/iopoll.h> >>> #include <linux/kernel.h> >>> +#include <linux/mfd/syscon.h> >>> #include <linux/module.h> >>> #include <linux/of.h> >>> #include <linux/of_device.h> >>> @@ -17,6 +18,7 @@ >>> #include <linux/phy/pcie.h> >>> #include <linux/phy/phy.h> >>> #include <linux/platform_device.h> >>> +#include <linux/regmap.h> >>> #include <linux/regulator/consumer.h> >>> #include <linux/reset.h> >>> #include <linux/slab.h> >>> @@ -886,6 +888,10 @@ static const struct qmp_phy_init_tbl sc8280xp_qmp_gen3x2_pcie_rc_serdes_tbl[] = >>> QMP_PHY_INIT_CFG(QSERDES_V5_COM_BIAS_EN_CLKBUFLR_EN, 0x14), >>> }; >>> >>> +static const struct qmp_phy_init_tbl sc8280xp_qmp_gen3x4_pcie_serdes_4ln_tbl[] = { >>> + QMP_PHY_INIT_CFG(QSERDES_V5_COM_BIAS_EN_CLKBUFLR_EN, 0x1c), >>> +}; >>> + >>> static const struct qmp_phy_init_tbl sc8280xp_qmp_gen3x1_pcie_tx_tbl[] = { >>> QMP_PHY_INIT_CFG(QSERDES_V5_TX_PI_QEC_CTRL, 0x20), >>> QMP_PHY_INIT_CFG(QSERDES_V5_TX_LANE_MODE_1, 0x75), >>> @@ -1491,6 +1497,9 @@ struct qmp_phy_cfg { >>> const struct qmp_phy_cfg_tables *tables_rc; >>> const struct qmp_phy_cfg_tables *tables_ep; >>> >>> + const struct qmp_phy_init_tbl *serdes_4ln_tbl; >>> + int serdes_4ln_num; >> >> Would it make more sense to change this into the proper >> qmp_phy_cfg_tables entry and then use the existing API for programming >> the table? > > No, there is just one serdes register update needed when in 4-lane mode, > besides programming tx/rx for the second port. Adding a third struct > qmp_phy_cfg_tables for this seems like overkill and would lead to a more > convoluted implementation of the programming sequence.
Ack. Let's have it this way and change it later if the need arises.
> > And you can't add it two one of the existing ones, as your comment seems > to suggest.
Please excuse me if I didn't write it clear enough. I suggested adding another cfg_tables, as you correctly commented above.
> > The gen3x4 PHYs can be in either 4-lane or 2-lane mode depending on the > TCSR configuration. Port A is programmed identically in both cases > except for this serdes register, and in 4-lane mode tx/rx also needs > to be programmed for port B. > >>> + >>> /* clock ids to be requested */ >>> const char * const *clk_list; >>> int num_clks; >>> @@ -1518,6 +1527,7 @@ struct qmp_pcie { >>> struct device *dev; >>> >>> const struct qmp_phy_cfg *cfg; >>> + bool tcsr_4ln_config; >> >> As a matter of preference, this seems too specific. I'd rename it to >> split_config or split_4ln_config. > > I'm afraid those names do not make much sense. This TCSR register > controls whether the PHY is in 4-lane mode (instead of 2-lane mode).
Well, we just need the info that it's 4-lane. It doesn't really matter if this information comes from TCSR, DT or e.g. fuses. I'd say that TCSR is a platform detail. Thus I'm suggesting a more generic name.
> >>> >>> void __iomem *serdes; >>> void __iomem *pcs; >>> @@ -1527,6 +1537,8 @@ struct qmp_pcie { >>> void __iomem *tx2; >>> void __iomem *rx2; >>> >>> + void __iomem *port_b; >>> + >>> struct clk *pipe_clk; >>> struct clk *pipediv2_clk; >>> struct clk_bulk_data *clks; >>> @@ -1932,6 +1944,44 @@ static const struct qmp_phy_cfg sc8280xp_qmp_gen3x2_pciephy_cfg = { >>> .phy_status = PHYSTATUS, >>> }; > >>> +static void qmp_pcie_init_port_b(struct qmp_pcie *qmp, const struct qmp_phy_cfg_tables *tbls) >>> +{ >>> + const struct qmp_phy_cfg *cfg = qmp->cfg; >>> + const struct qmp_pcie_offsets *offs = cfg->offsets; >>> + void __iomem *tx3, *rx3, *tx4, *rx4; >>> + >>> + tx3 = qmp->port_b + offs->tx; >>> + rx3 = qmp->port_b + offs->rx; >>> + tx4 = qmp->port_b + offs->tx2; >>> + rx4 = qmp->port_b + offs->rx2; >>> + >>> + qmp_pcie_configure_lane(tx3, tbls->tx, tbls->tx_num, 1); >>> + qmp_pcie_configure_lane(rx3, tbls->rx, tbls->rx_num, 1); >>> + >>> + qmp_pcie_configure_lane(tx4, tbls->tx, tbls->tx_num, 2); >>> + qmp_pcie_configure_lane(rx4, tbls->rx, tbls->rx_num, 2); >> >> I'd use BIT(2) and BIT(3) here. This would allow one to make a >> difference between programming first pair of lanes and second pair of >> lanes if necessary. > > No, the tx and tx registers of the second port should be programmed > identically to that of the first port.
As you would prefer. As a matter of fact, we do not have CFG_LANES in the PCIe PHY. Thus I'm surprised that you didn't drop this. I think CFG_LANES usage is limited to sm8250 USB and combo PHY configurations.
> >>> +} >>> + >>> static void qmp_pcie_init_registers(struct qmp_pcie *qmp, const struct qmp_phy_cfg_tables *tbls) >>> { >>> const struct qmp_phy_cfg *cfg = qmp->cfg; >>> @@ -2080,6 +2148,11 @@ static void qmp_pcie_init_registers(struct qmp_pcie *qmp, const struct qmp_phy_c >>> >>> qmp_pcie_configure(pcs, tbls->pcs, tbls->pcs_num); >>> qmp_pcie_configure(pcs_misc, tbls->pcs_misc, tbls->pcs_misc_num); >>> + >>> + if (cfg->lanes >= 4 && qmp->tcsr_4ln_config) { >>> + qmp_pcie_configure(serdes, cfg->serdes_4ln_tbl, cfg->serdes_4ln_num); >>> + qmp_pcie_init_port_b(qmp, tbls); >>> + } >> >> As you have been refactoring this piece of code, maybe it would make >> more sense to change qmp->tx/tx2 into an array of two elements? Then we >> can extend it to 4 in this patch, and just always write the whole array >> in a loop? > > No, I don't think that would be an improvement and would obscure the > fact that we're programming two otherwise identical ports (e.g. tx1 and > tx2 of port B is used for the third and fourth lanes). > > Note that the above conditional encodes the difference in programming > sequence between 4-lane and 2-lane mode I described above (one serdes > register difference + tx/rx of port b).
Either way looks fine to me. So, let's leave this in a way you've implemented it.
-- With best wishes Dmitry
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