mmc: rtsx_usb_sdmmc: Add 74 clocks in poweron flow

To conform with SD spec definition, that the host must provide at least 74
clocks before issuing first command, let's add these clock cycles at
MMC_POWER_UP.

Signed-off-by: Ricky Wu <ricky_wu@realtek.com>
Link: https://lore.kernel.org/r/20250616064956.1846258-1-ricky_wu@realtek.com
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

diff --git a/drivers/mmc/host/rtsx_usb_sdmmc.c b/drivers/mmc/host/rtsx_usb_sdmmc.c
index b750e2166d92a08073b9b7546ebf21b48d52b0fe..591d372066540fad86fc0edd2b721ff8b8860780 100644 (file)
--- a/drivers/mmc/host/rtsx_usb_sdmmc.c
+++ b/drivers/mmc/host/rtsx_usb_sdmmc.c
@@ -1014,6 +1014,7 @@ static void sd_set_power_mode(struct rtsx_usb_sdmmc *host,
                unsigned char power_mode)
 {
        int err;
+       struct rtsx_ucr *ucr = host->ucr;
 
        if (power_mode == host->power_mode)
                return;
@@ -1031,9 +1032,13 @@ static void sd_set_power_mode(struct rtsx_usb_sdmmc *host,
                err = sd_power_on(host);
                if (err)
                        dev_dbg(sdmmc_dev(host), "power-on (err = %d)\n", err);
+               /* issue the clock signals to card at least 74 clocks */
+               rtsx_usb_write_register(ucr, SD_BUS_STAT, SD_CLK_TOGGLE_EN, SD_CLK_TOGGLE_EN);
                break;
 
        case MMC_POWER_ON:
+               /* stop to send the clock signals */
+               rtsx_usb_write_register(ucr, SD_BUS_STAT, SD_CLK_TOGGLE_EN, 0x00);
        case MMC_POWER_UNDEFINED:
                break;