From: Loic Poulain loic.poulain@linaro.org
commit a89e7bcb18081c611eb6cf50edd440fa4983a71a upstream.
The Clock Data Recovery (CDR) circuit allows to automatically adjust the RX sampling-point/phase for high frequency cards (SDR104, HS200...). CDR is automatically enabled during DLL configuration. However, according to the APQ8016 reference manual, this function must be disabled during TX and tuning phase in order to prevent any interferences during tuning challenges and unexpected phase alteration during TX transfers.
This patch enables/disables CDR according to the current transfer mode.
This fixes sporadic write transfer issues observed with some SDR104 and HS200 cards.
Inspired by sdhci-msm downstream patch: https://chromium-review.googlesource.com/c/chromiumos/third_party/kernel/+/4...
Reported-by: Leonid Segal leonid.s@variscite.com Reported-by: Manabu Igusa migusa@arrowjapan.com Signed-off-by: Loic Poulain loic.poulain@linaro.org Acked-by: Adrian Hunter adrian.hunter@intel.com Acked-by: Georgi Djakov georgi.djakov@linaro.org Signed-off-by: Ulf Hansson ulf.hansson@linaro.org [georgi: backport to v4.19+] Signed-off-by: Georgi Djakov georgi.djakov@linaro.org --- drivers/mmc/host/sdhci-msm.c | 43 +++++++++++++++++++++++++++++++++++- 1 file changed, 42 insertions(+), 1 deletion(-)
diff --git a/drivers/mmc/host/sdhci-msm.c b/drivers/mmc/host/sdhci-msm.c index 3cc8bfee6c18..8594659cb592 100644 --- a/drivers/mmc/host/sdhci-msm.c +++ b/drivers/mmc/host/sdhci-msm.c @@ -258,6 +258,8 @@ struct sdhci_msm_host { bool mci_removed; const struct sdhci_msm_variant_ops *var_ops; const struct sdhci_msm_offset *offset; + bool use_cdr; + u32 transfer_mode; };
static const struct sdhci_msm_offset *sdhci_priv_msm_offset(struct sdhci_host *host) @@ -1025,6 +1027,26 @@ static int sdhci_msm_hs400_dll_calibration(struct sdhci_host *host) return ret; }
+static void sdhci_msm_set_cdr(struct sdhci_host *host, bool enable) +{ + const struct sdhci_msm_offset *msm_offset = sdhci_priv_msm_offset(host); + u32 config, oldconfig = readl_relaxed(host->ioaddr + + msm_offset->core_dll_config); + + config = oldconfig; + if (enable) { + config |= CORE_CDR_EN; + config &= ~CORE_CDR_EXT_EN; + } else { + config &= ~CORE_CDR_EN; + config |= CORE_CDR_EXT_EN; + } + + if (config != oldconfig) + writel_relaxed(config, host->ioaddr + + msm_offset->core_dll_config); +} + static int sdhci_msm_execute_tuning(struct mmc_host *mmc, u32 opcode) { struct sdhci_host *host = mmc_priv(mmc); @@ -1042,8 +1064,14 @@ static int sdhci_msm_execute_tuning(struct mmc_host *mmc, u32 opcode) if (host->clock <= CORE_FREQ_100MHZ || !(ios.timing == MMC_TIMING_MMC_HS400 || ios.timing == MMC_TIMING_MMC_HS200 || - ios.timing == MMC_TIMING_UHS_SDR104)) + ios.timing == MMC_TIMING_UHS_SDR104)) { + msm_host->use_cdr = false; + sdhci_msm_set_cdr(host, false); return 0; + } + + /* Clock-Data-Recovery used to dynamically adjust RX sampling point */ + msm_host->use_cdr = true;
/* * For HS400 tuning in HS200 timing requires: @@ -1525,6 +1553,19 @@ static int __sdhci_msm_check_write(struct sdhci_host *host, u16 val, int reg) case SDHCI_POWER_CONTROL: req_type = !val ? REQ_BUS_OFF : REQ_BUS_ON; break; + case SDHCI_TRANSFER_MODE: + msm_host->transfer_mode = val; + break; + case SDHCI_COMMAND: + if (!msm_host->use_cdr) + break; + if ((msm_host->transfer_mode & SDHCI_TRNS_READ) && + SDHCI_GET_CMD(val) != MMC_SEND_TUNING_BLOCK_HS200 && + SDHCI_GET_CMD(val) != MMC_SEND_TUNING_BLOCK) + sdhci_msm_set_cdr(host, true); + else + sdhci_msm_set_cdr(host, false); + break; }
if (req_type) {