[incubator-nuttx] 01/05: arch/arm/src/sam34/sam_hsmci.c: delay required after sending command

[xi...@apache.org]

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xiaoxiang pushed a commit to branch master
in repository https://gitbox.apache.org/repos/asf/incubator-nuttx.git

commit bc7f4b2375438951e7cdd26fe28e049068f9bfb3
Author: Richard Tucker <rt...@mookins.com>
AuthorDate: Tue Mar 22 16:55:50 2022 +1100

    arch/arm/src/sam34/sam_hsmci.c: delay required after sending command
---
 arch/arm/src/sam34/sam_hsmci.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/arch/arm/src/sam34/sam_hsmci.c b/arch/arm/src/sam34/sam_hsmci.c
index 8cc0f95ea1..86f27a83ac 100644
--- a/arch/arm/src/sam34/sam_hsmci.c
+++ b/arch/arm/src/sam34/sam_hsmci.c
@@ -41,6 +41,7 @@
 #include <nuttx/mmcsd.h>
 
 #include <nuttx/irq.h>
+#include <nuttx/signal.h>
 #include <arch/board/board.h>
 
 #include "chip.h"
@@ -1800,6 +1801,19 @@ static int sam_sendcmd(FAR struct sdio_dev_s *dev,
          cmd, arg, regval);
   putreg32(regval, SAM_HSMCI_CMDR);
   sam_cmdsample1(SAMPLENDX_AFTER_CMDR);
+
+  /* Card initialisation is unsuccessful without the following delay.
+   *
+   * It appears the timing from writing SAM_HSMCI_CMDR to calling
+   * sam_waitresponse is too short.
+   *
+   * For now the simplest solution is to add this delay.
+   * Further investigation is required to find the root cause and
+   * correct solution.
+   */
+
+  nxsig_usleep(10);
+
   return OK;
 }