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Message-ID: <1320d1a3-0554-4fbe-a2f2-7f6d4f50a3c4@intel.com>
Date: Thu, 16 Oct 2025 09:24:58 +0300
From: Adrian Hunter <adrian.hunter@...el.com>
To: Ram Prakash Gupta <quic_rampraka@...cinc.com>, Ulf Hansson
<ulf.hansson@...aro.org>, Rob Herring <robh@...nel.org>, Krzysztof Kozlowski
<krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, Bjorn Andersson
<andersson@...nel.org>, Konrad Dybcio <konradybcio@...nel.org>
CC: <linux-mmc@...r.kernel.org>, <devicetree@...r.kernel.org>,
<linux-kernel@...r.kernel.org>, <linux-arm-msm@...r.kernel.org>,
<dmitry.baryshkov@....qualcomm.com>, <quic_pragalla@...cinc.com>,
<quic_sayalil@...cinc.com>, <quic_nitirawa@...cinc.com>,
<quic_bhaskarv@...cinc.com>, <kernel@....qualcomm.com>, Sachin Gupta
<quic_sachgupt@...cinc.com>
Subject: Re: [PATCH v5 4/4] mmc: sdhci-msm: Rectify DLL programming sequence
for SDCC
On 13/10/2025 17:53, Ram Prakash Gupta wrote:
> From: Sachin Gupta <quic_sachgupt@...cinc.com>
>
> With the current DLL sequence stability issues for data
> transfer seen in HS400 and HS200 modes.
>
> "mmc0: cqhci: error IRQ status: 0x00000000 cmd error -84
> data error 0"
>
> Rectify the DLL programming sequence as per latest hardware
> programming guide
>
> Signed-off-by: Sachin Gupta <quic_sachgupt@...cinc.com>
> Signed-off-by: Ram Prakash Gupta <quic_rampraka@...cinc.com>
> ---
> drivers/mmc/host/sdhci-msm.c | 272 ++++++++++++++++++++++++++++++++---
> 1 file changed, 253 insertions(+), 19 deletions(-)
>
> diff --git a/drivers/mmc/host/sdhci-msm.c b/drivers/mmc/host/sdhci-msm.c
> index 8038b8def355..a875e92f8663 100644
> --- a/drivers/mmc/host/sdhci-msm.c
> +++ b/drivers/mmc/host/sdhci-msm.c
> @@ -28,6 +28,7 @@
> #define CORE_VERSION_MAJOR_SHIFT 28
> #define CORE_VERSION_MAJOR_MASK (0xf << CORE_VERSION_MAJOR_SHIFT)
> #define CORE_VERSION_MINOR_MASK 0xff
> +#define SDHCI_MSM_MIN_V_7FF 0x6e
>
> #define CORE_MCI_GENERICS 0x70
> #define SWITCHABLE_SIGNALING_VOLTAGE BIT(29)
> @@ -119,7 +120,8 @@
> #define CORE_PWRSAVE_DLL BIT(3)
>
> #define DDR_CONFIG_POR_VAL 0x80040873
> -
> +#define DLL_CONFIG_3_POR_VAL 0x10
> +#define TCXO_FREQ 19200000
>
> #define INVALID_TUNING_PHASE -1
> #define SDHCI_MSM_MIN_CLOCK 400000
> @@ -319,6 +321,16 @@ struct sdhci_msm_host {
> bool artanis_dll;
> };
>
> +enum dll_init_context {
> + DLL_INIT_NORMAL,
> + DLL_INIT_FROM_CX_COLLAPSE_EXIT,
DLL_INIT_FROM_CX_COLLAPSE_EXIT is never used?
> +};
> +
> +enum mode {
> + HS400, // equivalent to SDR104 mode for DLL.
> + HS200, // equivalent to SDR50 mode for DLL.
> +};
> +
> static const struct sdhci_msm_offset *sdhci_priv_msm_offset(struct sdhci_host *host)
> {
> struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
> @@ -803,6 +815,209 @@ static int msm_init_cm_dll(struct sdhci_host *host)
> return 0;
> }
>
> +static unsigned int sdhci_msm_get_min_clock(struct sdhci_host *host)
> +{
> + return SDHCI_MSM_MIN_CLOCK;
> +}
> +
> +static unsigned int sdhci_msm_get_clk_rate(struct sdhci_host *host, u32 req_clk)
> +{
> + struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
> + struct sdhci_msm_host *msm_host = sdhci_pltfm_priv(pltfm_host);
> + struct clk *core_clk = msm_host->bulk_clks[0].clk;
> + struct mmc_ios ios = host->mmc->ios;
> + unsigned int sup_clk;
> +
> + if (req_clk < sdhci_msm_get_min_clock(host))
> + return sdhci_msm_get_min_clock(host);
> +
> + sup_clk = clk_get_rate(core_clk);
> +
> + if (ios.timing == MMC_TIMING_MMC_HS400 ||
> + host->flags & SDHCI_HS400_TUNING)
> + sup_clk = sup_clk / 2;
> +
> + return sup_clk;
> +}
> +
> +/* Initialize the DLL (Programmable Delay Line) */
> +static int sdhci_msm_configure_dll(struct sdhci_host *host, enum dll_init_context
> + init_context, enum mode index)
> +{
> + struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
> + struct sdhci_msm_host *msm_host = sdhci_pltfm_priv(pltfm_host);
> + const struct sdhci_msm_offset *msm_offset = msm_host->offset;
> + struct mmc_host *mmc = host->mmc;
> + u32 ddr_cfg_offset, core_vendor_spec, config;
> + void __iomem *ioaddr = host->ioaddr;
> + unsigned long flags, dll_clock;
> + int rc = 0, wait_cnt = 50;
> +
> + dll_clock = sdhci_msm_get_clk_rate(host, host->clock);
> + spin_lock_irqsave(&host->lock, flags);
> +
> + core_vendor_spec = readl_relaxed(ioaddr + msm_offset->core_vendor_spec);
> +
> + /*
> + * Always disable PWRSAVE during the DLL power
> + * up regardless of its current setting.
> + */
> + core_vendor_spec &= ~CORE_CLK_PWRSAVE;
> + writel_relaxed(core_vendor_spec, ioaddr + msm_offset->core_vendor_spec);
> +
> + if (msm_host->use_14lpp_dll_reset) {
> + /* Disable CK_OUT */
> + config = readl_relaxed(ioaddr + msm_offset->core_dll_config);
> + config &= ~CORE_CK_OUT_EN;
> + writel_relaxed(config, ioaddr + msm_offset->core_dll_config);
> +
> + /* Disable the DLL clock */
> + config = readl_relaxed(ioaddr + msm_offset->core_dll_config_2);
> + config |= CORE_DLL_CLOCK_DISABLE;
> + writel_relaxed(config, ioaddr + msm_offset->core_dll_config_2);
> + }
> +
> + /*
> + * Write 1 to DLL_RST bit of DLL_CONFIG register
> + * and Write 1 to DLL_PDN bit of DLL_CONFIG register.
> + */
> + config = readl_relaxed(ioaddr + msm_offset->core_dll_config);
> + config |= (CORE_DLL_RST | CORE_DLL_PDN);
> + writel_relaxed(config, ioaddr + msm_offset->core_dll_config);
> +
> + /*
> + * Configure DLL_CONFIG_3 and USER_CTRL
> + * (Only applicable for 7FF projects).
> + */
> + if (msm_host->core_minor >= SDHCI_MSM_MIN_V_7FF) {
> + writel_relaxed(msm_host->dll[index].dll_config_3,
> + ioaddr + msm_offset->core_dll_config_3);
> + writel_relaxed(msm_host->dll[index].dll_usr_ctl,
> + ioaddr + msm_offset->core_dll_usr_ctl);
> + }
> +
> + /*
> + * Set DDR_CONFIG since step 7 is setting TEST_CTRL that can be skipped.
> + */
> + ddr_cfg_offset = msm_host->updated_ddr_cfg ? msm_offset->core_ddr_config
> + : msm_offset->core_ddr_config_old;
> +
> + config = msm_host->dll[index].ddr_config;
> + writel_relaxed(config, ioaddr + ddr_cfg_offset);
> +
> + /* Set DLL_CONFIG_2 */
> + if (msm_host->use_14lpp_dll_reset) {
> + u32 mclk_freq;
> + int cycle_cnt;
> +
> + /*
> + * Only configure the mclk_freq in normal DLL init
> + * context. If the DLL init is coming from
> + * CX Collapse Exit context, the host->clock may be zero.
> + * The DLL_CONFIG_2 register has already been restored to
> + * proper value prior to getting here.
> + */
> + if (init_context == DLL_INIT_NORMAL) {
> + cycle_cnt = readl_relaxed(ioaddr +
> + msm_offset->core_dll_config_2)
> + & CORE_FLL_CYCLE_CNT ? 8 : 4;
> +
> + mclk_freq = DIV_ROUND_CLOSEST_ULL(dll_clock * cycle_cnt, TCXO_FREQ);
> +
> + if (dll_clock < 100000000) {
> + pr_err("%s: %s: Non standard clk freq =%u\n",
> + mmc_hostname(mmc), __func__, dll_clock);
> + rc = -EINVAL;
> + goto out;
> + }
> +
> + config = readl_relaxed(ioaddr + msm_offset->core_dll_config_2);
> + config = (config & ~GENMASK(17, 10)) |
> + FIELD_PREP(GENMASK(17, 10), mclk_freq);
> + writel_relaxed(config, ioaddr + msm_offset->core_dll_config_2);
> + }
> + /* wait for 5us before enabling DLL clock */
> + udelay(5);
> + }
> +
> + config = msm_host->dll[index].dll_config;
> + writel_relaxed(config, ioaddr + msm_offset->core_dll_config);
> +
> + /* Wait for 52us */
> + spin_unlock_irqrestore(&host->lock, flags);
> + usleep_range(60, 70);
> + spin_lock_irqsave(&host->lock, flags);
> +
> + /*
> + * Write 0 to DLL_RST bit of DLL_CONFIG register
> + * and Write 0 to DLL_PDN bit of DLL_CONFIG register.
> + */
> + config &= ~CORE_DLL_RST;
> + writel_relaxed(config, ioaddr + msm_offset->core_dll_config);
> +
> + config &= ~CORE_DLL_PDN;
> + writel_relaxed(config, ioaddr + msm_offset->core_dll_config);
> + /* Write 1 to DLL_RST bit of DLL_CONFIG register */
> + config |= CORE_DLL_RST;
> + writel_relaxed(config, ioaddr + msm_offset->core_dll_config);
> +
> + /* Write 0 to DLL_RST bit of DLL_CONFIG register */
> + config &= ~CORE_DLL_RST;
> + writel_relaxed(config, ioaddr + msm_offset->core_dll_config);
> +
> + /* Set CORE_DLL_CLOCK_DISABLE to 0 */
> + if (msm_host->use_14lpp_dll_reset) {
> + config = readl_relaxed(ioaddr + msm_offset->core_dll_config_2);
> + config &= ~CORE_DLL_CLOCK_DISABLE;
> + writel_relaxed(config, ioaddr + msm_offset->core_dll_config_2);
> + }
> +
> + /* Set DLL_EN bit to 1. */
> + config = readl_relaxed(ioaddr + msm_offset->core_dll_config);
> + config |= CORE_DLL_EN;
> + writel_relaxed(config, ioaddr + msm_offset->core_dll_config);
> +
> + /*
> + * Wait for 8000 input clock. Here we calculate the
> + * delay from fixed clock freq 192MHz, which turns out 42us.
> + */
> + spin_unlock_irqrestore(&host->lock, flags);
> + usleep_range(50, 60);
> + spin_lock_irqsave(&host->lock, flags);
> +
> + /* Set CK_OUT_EN bit to 1. */
> + config |= CORE_CK_OUT_EN;
> + writel_relaxed(config, ioaddr + msm_offset->core_dll_config);
> +
> + /*
> + * Wait until DLL_LOCK bit of DLL_STATUS register
> + * becomes '1'.
> + */
> + while (!(readl_relaxed(ioaddr + msm_offset->core_dll_status) &
> + CORE_DLL_LOCK)) {
> + /* max. wait for 50us sec for LOCK bit to be set */
> + if (--wait_cnt == 0) {
> + dev_err(mmc_dev(mmc), "%s: DLL failed to LOCK\n",
> + mmc_hostname(mmc));
> + rc = -ETIMEDOUT;
> + goto out;
> + }
> + /* wait for 1us before polling again */
> + udelay(1);
> + }
Please use an iopoll macro like readl_relaxed_poll_timeout_atomic().
> +
> +out:
> + if (core_vendor_spec & CORE_CLK_PWRSAVE) {
> + /* Reenable PWRSAVE as needed */
> + config = readl_relaxed(ioaddr + msm_offset->core_vendor_spec);
> + config |= CORE_CLK_PWRSAVE;
> + writel_relaxed(config, ioaddr + msm_offset->core_vendor_spec);
> + }
> +
> + spin_unlock_irqrestore(&host->lock, flags);
> + return rc;
> +}
> +
> static void msm_hc_select_default(struct sdhci_host *host)
> {
> struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
> @@ -925,14 +1140,31 @@ static void sdhci_msm_hc_select_mode(struct sdhci_host *host)
> msm_hc_select_default(host);
> }
>
> +static int sdhci_msm_init_dll(struct sdhci_host *host, enum dll_init_context init_context)
> +{
> + if (host->mmc->ios.timing == MMC_TIMING_UHS_SDR104 ||
> + host->mmc->ios.timing == MMC_TIMING_MMC_HS400)
> + return sdhci_msm_configure_dll(host, init_context, HS400);
> +
> + return sdhci_msm_configure_dll(host, init_context, HS200);
> +}
> +
> +static int sdhci_msm_dll_config(struct sdhci_host *host, enum dll_init_context init_context)
> +{
> + struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
> + struct sdhci_msm_host *msm_host = sdhci_pltfm_priv(pltfm_host);
> +
> + return msm_host->artanis_dll ? sdhci_msm_init_dll(host, init_context) :
> + msm_init_cm_dll(host);
> +}
> +
> static int sdhci_msm_cdclp533_calibration(struct sdhci_host *host)
> {
> struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
> struct sdhci_msm_host *msm_host = sdhci_pltfm_priv(pltfm_host);
> + const struct sdhci_msm_offset *msm_offset = msm_host->offset;
> u32 config, calib_done;
> int ret;
> - const struct sdhci_msm_offset *msm_offset =
> - msm_host->offset;
>
> pr_debug("%s: %s: Enter\n", mmc_hostname(host->mmc), __func__);
>
> @@ -940,7 +1172,7 @@ static int sdhci_msm_cdclp533_calibration(struct sdhci_host *host)
> * Retuning in HS400 (DDR mode) will fail, just reset the
> * tuning block and restore the saved tuning phase.
> */
> - ret = msm_init_cm_dll(host);
> + ret = sdhci_msm_dll_config(host, DLL_INIT_NORMAL);
> if (ret)
> goto out;
>
> @@ -1028,7 +1260,7 @@ static int sdhci_msm_cdclp533_calibration(struct sdhci_host *host)
> return ret;
> }
>
> -static int sdhci_msm_cm_dll_sdc4_calibration(struct sdhci_host *host)
> +static int sdhci_msm_cm_dll_sdc4_calibration(struct sdhci_host *host, enum mode index)
> {
> struct mmc_host *mmc = host->mmc;
> u32 dll_status, config, ddr_cfg_offset;
> @@ -1051,7 +1283,11 @@ static int sdhci_msm_cm_dll_sdc4_calibration(struct sdhci_host *host)
> ddr_cfg_offset = msm_offset->core_ddr_config;
> else
> ddr_cfg_offset = msm_offset->core_ddr_config_old;
> - writel_relaxed(msm_host->ddr_config, host->ioaddr + ddr_cfg_offset);
> +
> + if (msm_host->artanis_dll)
> + writel_relaxed(msm_host->dll[index].ddr_config, host->ioaddr + ddr_cfg_offset);
> + else
> + writel_relaxed(msm_host->ddr_config, host->ioaddr + ddr_cfg_offset);
>
> if (mmc->ios.enhanced_strobe) {
> config = readl_relaxed(host->ioaddr +
> @@ -1108,11 +1344,10 @@ static int sdhci_msm_hs400_dll_calibration(struct sdhci_host *host)
> {
> struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
> struct sdhci_msm_host *msm_host = sdhci_pltfm_priv(pltfm_host);
> + const struct sdhci_msm_offset *msm_offset = msm_host->offset;
> struct mmc_host *mmc = host->mmc;
> - int ret;
> u32 config;
> - const struct sdhci_msm_offset *msm_offset =
> - msm_host->offset;
> + int ret;
Here and elsewhere, this re-ordering of local definitions is a nice
improvement but it would be better as a separate patch
>
> pr_debug("%s: %s: Enter\n", mmc_hostname(host->mmc), __func__);
>
> @@ -1120,7 +1355,8 @@ static int sdhci_msm_hs400_dll_calibration(struct sdhci_host *host)
> * Retuning in HS400 (DDR mode) will fail, just reset the
> * tuning block and restore the saved tuning phase.
> */
> - ret = msm_init_cm_dll(host);
> + ret = sdhci_msm_dll_config(host, DLL_INIT_NORMAL);
> +
> if (ret)
> goto out;
>
> @@ -1140,7 +1376,7 @@ static int sdhci_msm_hs400_dll_calibration(struct sdhci_host *host)
> if (msm_host->use_cdclp533)
> ret = sdhci_msm_cdclp533_calibration(host);
> else
> - ret = sdhci_msm_cm_dll_sdc4_calibration(host);
> + ret = sdhci_msm_cm_dll_sdc4_calibration(host, HS400);
> out:
> pr_debug("%s: %s: Exit, ret %d\n", mmc_hostname(host->mmc),
> __func__, ret);
> @@ -1183,7 +1419,8 @@ static int sdhci_msm_restore_sdr_dll_config(struct sdhci_host *host)
> return 0;
>
> /* Reset the tuning block */
> - ret = msm_init_cm_dll(host);
> + ret = sdhci_msm_dll_config(host, DLL_INIT_NORMAL);
> +
> if (ret)
> return ret;
>
> @@ -1257,12 +1494,11 @@ static int sdhci_msm_execute_tuning(struct mmc_host *mmc, u32 opcode)
> if (host->flags & SDHCI_HS400_TUNING) {
> sdhci_msm_hc_select_mode(host);
> msm_set_clock_rate_for_bus_mode(host, ios.clock);
> - host->flags &= ~SDHCI_HS400_TUNING;
> }
>
> retry:
> /* First of all reset the tuning block */
> - rc = msm_init_cm_dll(host);
> + rc = sdhci_msm_dll_config(host, DLL_INIT_NORMAL);
> if (rc)
> return rc;
>
> @@ -1325,6 +1561,9 @@ static int sdhci_msm_execute_tuning(struct mmc_host *mmc, u32 opcode)
> rc = -EIO;
> }
>
> + if (host->flags & SDHCI_HS400_TUNING)
> + host->flags &= ~SDHCI_HS400_TUNING;
Really the flag should be cleared on all return paths
> +
> if (!rc)
> msm_host->tuning_done = true;
> return rc;
> @@ -1845,11 +2084,6 @@ static unsigned int sdhci_msm_get_max_clock(struct sdhci_host *host)
> return clk_round_rate(core_clk, ULONG_MAX);
> }
>
> -static unsigned int sdhci_msm_get_min_clock(struct sdhci_host *host)
> -{
> - return SDHCI_MSM_MIN_CLOCK;
> -}
> -
> /*
> * __sdhci_msm_set_clock - sdhci_msm clock control.
> *
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