Merge branch 'feature/emmc_doc_ut_4bit_sdr' into 'master'

sdmmc_host: add unit tests and improve documents about using eMMC in 4-line SDR mode

See merge request espressif/esp-idf!13334

components/sdmmc/test/test_sd.c

@@ -133,13 +133,19 @@ TEST_CASE("probe SD, slot 1, 1-bit", "[sd][test_env=UT_T1_SDMODE]")
 }
 
 #ifdef WITH_EMMC_TEST
-TEST_CASE("probe eMMC, slot 0, 4-bit, DDR", "[sd][test_env=EMMC]")
+TEST_CASE("probe eMMC, slot 0, 4-bit", "[sd][test_env=EMMC]")
 {
+    //Test with SDR
+    probe_sd(SDMMC_HOST_SLOT_0, 4, SDMMC_FREQ_PROBING, 0);
+    probe_sd(SDMMC_HOST_SLOT_0, 4, SDMMC_FREQ_DEFAULT, 0);
+    probe_sd(SDMMC_HOST_SLOT_0, 4, SDMMC_FREQ_HIGHSPEED, 0);
+    //Test with DDR
     probe_sd(SDMMC_HOST_SLOT_0, 4, SDMMC_FREQ_HIGHSPEED, 1);
 }
 
 TEST_CASE("probe eMMC, slot 0, 8-bit", "[sd][test_env=EMMC]")
 {
+    //8-bit DDR not supported yet, test with SDR only
     probe_sd(SDMMC_HOST_SLOT_0, 8, SDMMC_FREQ_PROBING, 0);
     probe_sd(SDMMC_HOST_SLOT_0, 8, SDMMC_FREQ_DEFAULT, 0);
     probe_sd(SDMMC_HOST_SLOT_0, 8, SDMMC_FREQ_HIGHSPEED, 0);

docs/en/api-reference/peripherals/sdmmc_host.rst

@@ -51,8 +51,8 @@ Supported Speed Modes
 
 SDMMC Host driver supports the following speed modes:
 
-- Default Speed (20 MHz), 4-line/1-line (with SD cards), and 8-line (with 3.3 V eMMC)
-- High Speed (40 MHz), 4-line/1-line (with SD cards), and 8-line (with 3.3 V eMMC)
+- Default Speed (20 MHz), 1/4-line (with SD cards), and 1/4/8-line (with 3.3 V eMMC)
+- High Speed (40 MHz), 1/4-line (with SD cards), and 1/4/8-line (with 3.3 V eMMC)
 - High Speed DDR (40 MHz), 4-line (with 3.3 V eMMC)
 
 Speed modes not supported at present: