Refactor serial helpers to make resets easier

We were experience issues where the readPicture command would become
unresponsive after exactly 10 reads 32 bytes in size. We were able to
"solve" this by simply closing and re-opening the serial connection file
descriptor after reading a block. This may be a limitation in the le_tty
interface meaning it may be worth implementing this using only Linux
system calls (e.g open et al).

The sendCommand function now pays attention to the return status of the
calls to fd helpers.

1 files changed, 34 insertions, 11 deletions

diff --git a/camera.c b/camera.c
index 31e7221..ccd4b12 100644
--- a/camera.c
+++ b/camera.c
@@ -1,15 +1,25 @@
 #include "camera.h"
+#include "legato.h"
 
 COMPONENT_INIT { }
 
 // File descriptor is returned in the fd pointer
-le_result_t openCameraFd (const char *path, int *fd, tty_Speed_t baud, int nBytes, int timeout) {
-  *fd = le_tty_Open(path, O_RDWR | O_NOCTTY | O_NDELAY);
-  le_result_t baudRes = le_tty_SetBaudRate(*fd, baud);
-  le_result_t rawRes = le_tty_SetRaw(*fd, nBytes, timeout);
+le_result_t fd_openCam (int *fd) {
+  *fd = le_tty_Open(TTY_PATH, O_RDWR | O_NOCTTY | O_NDELAY);
+  le_result_t baudRes = le_tty_SetBaudRate(*fd, LE_TTY_SPEED_38400);
+  le_result_t rawRes = le_tty_SetRaw(*fd, CAM_BUFF_SIZE, TTY_TIMEOUT);
   return baudRes == LE_OK && rawRes == LE_OK ? LE_OK : LE_FAULT;
 }
 
+void fd_closeCam (int fd) {
+  return le_tty_Close(fd);
+}
+
+le_result_t fd_resetCamTty (int *fd) {
+  fd_closeCam(*fd);
+  return fd_openCam(fd);
+}
+
 ssize_t fd_getByte (int fd, uint8_t *data) {
   return read(fd, data, 1);
 }
@@ -19,6 +29,11 @@ int fd_dataAvail (int fd, int *data) {
 }
 
 void sendCommand (Camera *cam, uint8_t cmd, uint8_t args[], uint8_t nArgs) {
+  // TODO figure out the longest possible command
+  // as I doubt it's anywhere near 100
+  //
+  // The other (and probably better option) here would
+  // be to call malloc
   uint8_t toWrite[100] = { VC0706_PREFIX, cam->serialNum, cmd };
   int start = 3;
   int end = nArgs + start;
@@ -53,21 +68,22 @@ bool runCommandFlush (Camera *cam, uint8_t cmd, uint8_t args[], uint8_t nArgs, u
 uint8_t readResponse (Camera *cam, uint8_t nBytes, uint8_t timeout) {
   uint8_t counter = 0;
   cam->bufferLen = 0;
-  int avail;
+  int avail = 0;
   uint8_t data;
   while ((counter < timeout) && (cam->bufferLen < nBytes)) {
     // data is returned in avail pointer
-    fd_dataAvail(cam->fd, &avail);
+    int availRes = fd_dataAvail(cam->fd, &avail);
     // this case covers no data available
-    if (avail <= 0) {
+    // or when fd_dataAvail fails
+    if (avail <= 0 || availRes != 0) {
       usleep(1000);
       counter++;
       continue;
     }
     // this case is when we get data
     counter = 0;
-    fd_getByte(cam->fd, &data);
-    cam->buff[cam->bufferLen++] = data;
+    ssize_t bytesRead = fd_getByte(cam->fd, &data);
+    if (bytesRead > 0) cam->buff[cam->bufferLen++] = data;
   }
   return cam->bufferLen;
 }
@@ -75,7 +91,7 @@ uint8_t readResponse (Camera *cam, uint8_t nBytes, uint8_t timeout) {
 void printBuffer (Camera *cam) {
   LE_DEBUG("Printing cam buffer");
   for(int i = 0; i < NUM_ARRAY_MEMBERS(cam->buff); i++) {
-    LE_DEBUG("buff[%d]=%d", i, cam->buff[i]);
+    LE_DEBUG("buff[%d]=%x", i, cam->buff[i]);
   }
 }
 
@@ -302,9 +318,16 @@ bool readImageBlock (Camera *cam, FILE *filePtr) {
     }
     fwrite(buff, sizeof(*buff), bytesToRead, filePtr);
     jpgLen -= bytesToRead;
-    sleep(3);
+    // TODO figure out why resetting the resetting
+    // the serial connection after reading a block
+    // keeps the camera responsive
+    //
+    // This may be a limitation in le_tty
+    // so using Linux system calls may be worthwhile
+    fd_resetCamTty(&(cam->fd));
   }
   fclose(filePtr);
+  printBuffer(cam);
   return success;
 }