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Posted to commits@nuttx.apache.org by GitBox <gi...@apache.org> on 2022/03/24 22:35:28 UTC

[GitHub] [incubator-nuttx] rtucker85 commented on a change in pull request #5835: LITESDCARD peripheral driver support

rtucker85 commented on a change in pull request #5835:
URL: https://github.com/apache/incubator-nuttx/pull/5835#discussion_r834786849



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File path: include/nuttx/sdio.h
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@@ -477,6 +477,7 @@
 #define SDIO_CAPS_DMABEFOREWRITE  0x04 /* Bit 2=1: Executes DMA before write command */
 #define SDIO_CAPS_4BIT            0x08 /* Bit 3=1: Supports 4 bit operation */
 #define SDIO_CAPS_8BIT            0x10 /* Bit 4=1: Supports 8 bit operation */
+#define SDIO_CAPS_4BIT_ONLY       0x20 /* Bit 5=1: Supports 4-bit only operation */

Review comment:
       @AndrewD  Is correct. This peripheral _only_ supports 4 bit mode.
   I.e. It doesnt support 1bit _or_ 8bit modes.
   
   We therefore must have a mechanism to force the mmcsd driver to put the card into 4 bit mode without checking the capabilities of the card obtained from the SCR register.
   
   Reading the SCR register becomes redundant but has been left in place for diagnostic purposes - If DEBUG_FS_INFO is enabled.




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