Re: [PATCH 4/6] mmc: host: sdhci-esdhc-imx.c: correct the auto-tuning setting for sdio device
From: Ulf Hansson <hidden>
Date: 2021-08-16 13:53:53
Also in:
linux-arm-kernel, linux-mmc
On Mon, 16 Aug 2021 at 15:00, [off-list ref] wrote:
From: Haibo Chen <haibo.chen@nxp.com> USDHC contain auto tuning circuit, this circuit will work automatically after the tuning procedurae, it can increase/decrease the delay cell according to the outside environment change (like temperature). Unfortunately, this auto tuning circuit can not handle the async sdio device interrupt correctly. When sdio device use 4 data line, async sdio interrupt will use DAT[1], if we enable auto tuning circuit check 4 data lines, include the DAT[1], this circuit will detect this interrupt, take this as a data on DAT[1], and adjust the delay cell wrongly. This is the hardware design limitation, to avoid this, when sdio device enable async interrupt, auto tuning circuit only check DAT[0] and CMD lines.
SDIO irqs are being enabled/disabled dynamically in runtime by the mmc core via the host ops ->enable_sdio_irq(). Rather than forcing the autotuning circuit to stay unused statically, perhaps an option would be to disable it when the SDIO irqs becomes enabled? Or maybe that becomes too complicated?
quoted hunk ↗ jump to hunk
Signed-off-by: Haibo Chen <haibo.chen@nxp.com> --- drivers/mmc/host/sdhci-esdhc-imx.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+)diff --git a/drivers/mmc/host/sdhci-esdhc-imx.c b/drivers/mmc/host/sdhci-esdhc-imx.c index f18d169bc8ff..ab84c29777e5 100644 --- a/drivers/mmc/host/sdhci-esdhc-imx.c +++ b/drivers/mmc/host/sdhci-esdhc-imx.c@@ -226,6 +226,7 @@ struct esdhc_platform_data { unsigned int tuning_step; /* The delay cell steps in tuning procedure */ unsigned int tuning_start_tap; /* The start delay cell point in tuning procedure */ unsigned int strobe_dll_delay_target; /* The delay cell for strobe pad (read clock) */ + bool sdio_async_interrupt_enabled; /* sdio device enable the async interrupt */ }; struct esdhc_soc_data {@@ -416,6 +417,8 @@ static inline void esdhc_wait_for_card_clock_gate_off(struct sdhci_host *host) /* Enable the auto tuning circuit to check the CMD line and BUS line */ static inline void usdhc_auto_tuning_mode_sel(struct sdhci_host *host) { + struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host); + struct pltfm_imx_data *imx_data = sdhci_pltfm_priv(pltfm_host); u32 buswidth, auto_tune_buswidth; buswidth = USDHC_GET_BUSWIDTH(readl(host->ioaddr + SDHCI_HOST_CONTROL));@@ -432,6 +435,18 @@ static inline void usdhc_auto_tuning_mode_sel(struct sdhci_host *host) break; } + /* + * If sdio device use async interrupt, it will use DAT[1] to signal + * the device's interrupt asynchronous when use 4 data lines. + * Then hardware auto tuning circuit MUST NOT check the DAT[1] line, + * otherwise auto tuning will be impacted by this async interrupt, + * and change the delay cell incorrectly, which then cause data/cmd + * errors. + * This is the hardware auto tuning circuit limitation. + */ + if (imx_data->boarddata.sdio_async_interrupt_enabled) + auto_tune_buswidth = ESDHC_VEND_SPEC2_AUTO_TUNE_1BIT_EN; + esdhc_clrset_le(host, ESDHC_VEND_SPEC2_AUTO_TUNE_MODE_MASK, auto_tune_buswidth | ESDHC_VEND_SPEC2_AUTO_TUNE_CMD_EN, ESDHC_VEND_SPEC2);@@ -1531,6 +1546,9 @@ sdhci_esdhc_imx_probe_dt(struct platform_device *pdev, if (of_property_read_u32(np, "fsl,delay-line", &boarddata->delay_line)) boarddata->delay_line = 0; + if (of_property_read_bool(np, "fsl,sdio-async-interrupt-enabled"))
As stated on the DT patch, I think you can use the "cap-sdio-irq" instead.
+ boarddata->sdio_async_interrupt_enabled = true;
+
mmc_of_parse_voltage(host->mmc, &host->ocr_mask);
if (esdhc_is_usdhc(imx_data) && !IS_ERR(imx_data->pinctrl)) {
--
2.17.1Kind regards Uffe