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Mon, 23 Mar 2026 03:19:33 -0700 (PDT) From: Iker Pedrosa Date: Mon, 23 Mar 2026 11:19:06 +0100 Subject: [PATCH v4 3/8] mmc: sdhci-of-k1: add comprehensive SDR tuning support Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20260323-orangepi-sd-card-uhs-v4-3-567c9775fd0e@gmail.com> References: <20260323-orangepi-sd-card-uhs-v4-0-567c9775fd0e@gmail.com> In-Reply-To: <20260323-orangepi-sd-card-uhs-v4-0-567c9775fd0e@gmail.com> To: Ulf Hansson , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Adrian Hunter , Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexandre Ghiti , Yixun Lan , Yixun Lan Cc: Michael Opdenacker , Javier Martinez Canillas , linux-mmc@vger.kernel.org, devicetree@vger.kernel.org, linux-riscv@lists.infradead.org, spacemit@lists.linux.dev, linux-kernel@vger.kernel.org, Iker Pedrosa , Anand Moon , Trevor Gamblin X-Mailer: b4 0.14.2 Implement software tuning algorithm to enable UHS-I SDR modes for SD card operation and HS200 mode for eMMC. This adds both TX and RX delay line tuning based on the SpacemiT K1 controller capabilities. Algorithm features: - Add tuning register definitions (RX_CFG, DLINE_CTRL, DLINE_CFG) - Conditional tuning: only for high-speed modes (=E2=89=A5100MHz) - TX tuning: configure transmit delay line with optimal values (dline_reg=3D0, delaycode=3D127) to ensure optimal signal output timing - RX tuning: single-pass window detection algorithm testing full delay range (0-255) to find optimal receive timing window - Retry mechanism: multiple fallback delays within optimal window for improved reliability Tested-by: Anand Moon Acked-by: Adrian Hunter Tested-by: Trevor Gamblin Signed-off-by: Iker Pedrosa --- drivers/mmc/host/sdhci-of-k1.c | 172 +++++++++++++++++++++++++++++++++++++= ++++ 1 file changed, 172 insertions(+) diff --git a/drivers/mmc/host/sdhci-of-k1.c b/drivers/mmc/host/sdhci-of-k1.c index 234e258af25996e7bbcd0b70366c7480bf62bee7..5432c94680d8c1c1555b5fb906a= dbc881953dd05 100644 --- a/drivers/mmc/host/sdhci-of-k1.c +++ b/drivers/mmc/host/sdhci-of-k1.c @@ -69,6 +69,28 @@ #define SDHC_PHY_DRIVE_SEL GENMASK(2, 0) #define SDHC_RX_BIAS_CTRL BIT(5) =20 +#define SPACEMIT_SDHC_RX_CFG_REG 0x118 +#define SDHC_RX_SDCLK_SEL0_MASK GENMASK(1, 0) +#define SDHC_RX_SDCLK_SEL1_MASK GENMASK(3, 2) +#define SDHC_RX_SDCLK_SEL1 FIELD_PREP(SDHC_RX_SDCLK_SEL1_MASK= , 1) + +#define SPACEMIT_SDHC_DLINE_CTRL_REG 0x130 +#define SDHC_DLINE_PU BIT(0) +#define SDHC_RX_DLINE_CODE_MASK GENMASK(23, 16) +#define SDHC_TX_DLINE_CODE_MASK GENMASK(31, 24) + +#define SPACEMIT_SDHC_DLINE_CFG_REG 0x134 +#define SDHC_RX_DLINE_REG_MASK GENMASK(7, 0) +#define SDHC_RX_DLINE_GAIN BIT(8) +#define SDHC_TX_DLINE_REG_MASK GENMASK(23, 16) + +#define SPACEMIT_RX_DLINE_REG 9 +#define SPACEMIT_RX_TUNE_DELAY_MIN 0x0 +#define SPACEMIT_RX_TUNE_DELAY_MAX 0xFF + +#define SPACEMIT_TX_TUNING_DLINE_REG 0x00 +#define SPACEMIT_TX_TUNING_DELAYCODE 127 + struct spacemit_sdhci_host { struct clk *clk_core; struct clk *clk_io; @@ -96,6 +118,50 @@ static inline void spacemit_sdhci_clrsetbits(struct sdh= ci_host *host, u32 clr, u sdhci_writel(host, val, reg); } =20 +static void spacemit_sdhci_set_rx_delay(struct sdhci_host *host, u8 delay) +{ + spacemit_sdhci_clrsetbits(host, SDHC_RX_DLINE_CODE_MASK, + FIELD_PREP(SDHC_RX_DLINE_CODE_MASK, delay), + SPACEMIT_SDHC_DLINE_CTRL_REG); +} + +static void spacemit_sdhci_set_tx_delay(struct sdhci_host *host, u8 delay) +{ + spacemit_sdhci_clrsetbits(host, SDHC_TX_DLINE_CODE_MASK, + FIELD_PREP(SDHC_TX_DLINE_CODE_MASK, delay), + SPACEMIT_SDHC_DLINE_CTRL_REG); +} + +static void spacemit_sdhci_set_tx_dline_reg(struct sdhci_host *host, u8 dl= ine_reg) +{ + spacemit_sdhci_clrsetbits(host, SDHC_TX_DLINE_REG_MASK, + FIELD_PREP(SDHC_TX_DLINE_REG_MASK, dline_reg), + SPACEMIT_SDHC_DLINE_CFG_REG); +} + +static void spacemit_sdhci_tx_tuning_prepare(struct sdhci_host *host) +{ + spacemit_sdhci_setbits(host, SDHC_TX_MUX_SEL, SPACEMIT_SDHC_TX_CFG_REG); + spacemit_sdhci_setbits(host, SDHC_DLINE_PU, SPACEMIT_SDHC_DLINE_CTRL_REG); + udelay(5); +} + +static void spacemit_sdhci_prepare_tuning(struct sdhci_host *host) +{ + spacemit_sdhci_clrsetbits(host, SDHC_RX_DLINE_REG_MASK, + FIELD_PREP(SDHC_RX_DLINE_REG_MASK, SPACEMIT_RX_DLINE_REG), + SPACEMIT_SDHC_DLINE_CFG_REG); + + spacemit_sdhci_setbits(host, SDHC_DLINE_PU, SPACEMIT_SDHC_DLINE_CTRL_REG); + udelay(5); + + spacemit_sdhci_clrsetbits(host, SDHC_RX_SDCLK_SEL1_MASK, SDHC_RX_SDCLK_SE= L1, + SPACEMIT_SDHC_RX_CFG_REG); + + if (host->mmc->ios.timing =3D=3D MMC_TIMING_MMC_HS200) + spacemit_sdhci_setbits(host, SDHC_HS200_USE_RFIFO, SPACEMIT_SDHC_PHY_FUN= C_REG); +} + static void spacemit_sdhci_reset(struct sdhci_host *host, u8 mask) { sdhci_reset(host, mask); @@ -191,6 +257,111 @@ static unsigned int spacemit_sdhci_clk_get_max_clock(= struct sdhci_host *host) return clk_get_rate(pltfm_host->clk); } =20 +static int spacemit_sdhci_execute_tuning(struct sdhci_host *host, u32 opco= de) +{ + int current_len =3D 0, current_start =3D 0; + int max_pass_len =3D 0, max_pass_start =3D 0; + struct mmc_host *mmc =3D host->mmc; + struct mmc_ios ios =3D mmc->ios; + u8 final_delay; + int ret =3D 0; + int i; + + /* + * Tuning is required for SDR50/SDR104, HS200/HS400 cards and + * if clock frequency is greater than 100MHz in these modes. + */ + if (host->clock < 100 * 1000 * 1000 || + !(ios.timing =3D=3D MMC_TIMING_MMC_HS200 || + ios.timing =3D=3D MMC_TIMING_UHS_SDR50 || + ios.timing =3D=3D MMC_TIMING_UHS_SDR104)) + return 0; + + if (mmc->caps2 & MMC_CAP2_NO_MMC) { + spacemit_sdhci_set_tx_dline_reg(host, SPACEMIT_TX_TUNING_DLINE_REG); + spacemit_sdhci_set_tx_delay(host, SPACEMIT_TX_TUNING_DELAYCODE); + spacemit_sdhci_tx_tuning_prepare(host); + + dev_dbg(mmc_dev(host->mmc), "TX tuning: dline_reg=3D%d, delaycode=3D%d\n= ", + SPACEMIT_TX_TUNING_DLINE_REG, SPACEMIT_TX_TUNING_DELAYCODE); + } + + spacemit_sdhci_prepare_tuning(host); + + for (i =3D SPACEMIT_RX_TUNE_DELAY_MIN; i <=3D SPACEMIT_RX_TUNE_DELAY_MAX;= i++) { + spacemit_sdhci_set_rx_delay(host, i); + ret =3D mmc_send_tuning(host->mmc, opcode, NULL); + + dev_dbg(mmc_dev(host->mmc), "RX delay %d: %s\n", + i, ret =3D=3D 0 ? "pass" : "fail"); + + if (ret =3D=3D 0) { + /* Test passed - extend current window */ + if (current_len =3D=3D 0) + current_start =3D i; + current_len++; + } else { + /* Test failed - check if current window is best so far */ + if (current_len > max_pass_len) { + max_pass_len =3D current_len; + max_pass_start =3D current_start; + } + current_len =3D 0; + } + } + + if (current_len > max_pass_len) { + max_pass_len =3D current_len; + max_pass_start =3D current_start; + } + + if (max_pass_len < 3) { + dev_err(mmc_dev(host->mmc), "Tuning failed: no stable window found\n"); + return -EIO; + } + + final_delay =3D max_pass_start + max_pass_len / 2; + spacemit_sdhci_set_rx_delay(host, final_delay); + ret =3D mmc_send_tuning(host->mmc, opcode, NULL); + if (ret) { + u8 retry_delays[] =3D { + max_pass_start + max_pass_len / 4, + max_pass_start + (3 * max_pass_len) / 4, + max_pass_start, + max_pass_start + max_pass_len - 1 + }; + int retry_count =3D ARRAY_SIZE(retry_delays); + + dev_warn(mmc_dev(mmc), "Primary delay %d failed, trying alternatives\n", + final_delay); + + for (i =3D 0; i < retry_count; i++) { + if (retry_delays[i] >=3D SPACEMIT_RX_TUNE_DELAY_MIN && + retry_delays[i] <=3D SPACEMIT_RX_TUNE_DELAY_MAX) { + spacemit_sdhci_set_rx_delay(host, retry_delays[i]); + ret =3D mmc_send_tuning(host->mmc, opcode, NULL); + if (!ret) { + final_delay =3D retry_delays[i]; + dev_info(mmc_dev(mmc), "Retry successful with delay %d\n", + final_delay); + break; + } + } + } + + if (ret) { + dev_err(mmc_dev(mmc), "All retry attempts failed\n"); + return -EIO; + } + } + + dev_dbg(mmc_dev(host->mmc), + "Tuning successful: window %d-%d, using delay %d\n", + max_pass_start, max_pass_start + max_pass_len - 1, final_delay); + + return 0; +} + static int spacemit_sdhci_pre_select_hs400(struct mmc_host *mmc) { struct sdhci_host *host =3D mmc_priv(mmc); @@ -326,6 +497,7 @@ static const struct sdhci_ops spacemit_sdhci_ops =3D { .set_bus_width =3D sdhci_set_bus_width, .set_clock =3D spacemit_sdhci_set_clock, .set_uhs_signaling =3D spacemit_sdhci_set_uhs_signaling, + .platform_execute_tuning =3D spacemit_sdhci_execute_tuning, }; =20 static const struct sdhci_pltfm_data spacemit_sdhci_k1_pdata =3D { --=20 2.53.0