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Message-ID: <80ff9d78-3ee9-6e0b-eaf7-46d6eabb4d25@quicinc.com>
Date: Wed, 22 Oct 2025 12:15:53 +0530
From: Ram Prakash Gupta <quic_rampraka@...cinc.com>
To: Adrian Hunter <adrian.hunter@...el.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 10/16/2025 11:54 AM, Adrian Hunter wrote:
> 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?
This is ball parked for a collapse scenario, but that is yet to be
added, will remove this for time being in next patchset.
>
>> +};
>> +
>> +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().
sure, thanks, will explore and update accordingly.
>
>> +
>> +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
sure will update separately, will remove this change in next patchset.
>
>>
>> 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
Primary reason for moving this here is to have the flag set during
sdhci_msm_dll_config(), for right clk division as per requirement,
so to keep it clear, I ll move just after sdhci_msm_dll_config()
then no other path would come into picture.
>
>> +
>> 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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