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console: Keep ->start() and ->stop() balanced

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There is no need to call ->start() for already started device. All the same,
there is no need to call ->stop() for devices still in use.

For now enforce this only for IOMUX case.

Cc: Simon Glass <sjg@chromium.org>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
This commit is contained in:
Andy Shevchenko 2020-12-21 14:30:01 +02:00 committed by Tom Rini
parent 41f668b97c
commit 95aaf40254
1 changed files with 37 additions and 0 deletions
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37
common/console.c
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@ -237,6 +237,32 @@ static void __maybe_unused console_devices_set(int file, struct stdio_dev *dev)
console_devices[file][0] = dev;
}
/**
* console_needs_start_stop() - check if we need to start or stop the STDIO device
* @file: STDIO file
* @sdev: STDIO device in question
*
* This function checks if we need to start or stop the stdio device used for
* a console. For IOMUX case it simply enforces one time start and one time
* stop of the device independently of how many STDIO files are using it. In
* other words, we start console once before first STDIO device wants it and
* stop after the last is gone.
*/
static bool console_needs_start_stop(int file, struct stdio_dev *sdev)
{
int i, j;
for (i = 0; i < ARRAY_SIZE(cd_count); i++) {
if (i == file)
continue;
for (j = 0; j < cd_count[i]; j++)
if (console_devices[i][j] == sdev)
return false;
}
return true;
}
/*
* This depends on tstc() always being called before getchar().
* This is guaranteed to be true because this routine is called
@ -346,6 +372,11 @@ static void __maybe_unused console_devices_set(int file, struct stdio_dev *dev)
{
}
static inline bool console_needs_start_stop(int file, struct stdio_dev *sdev)
{
return true;
}
static inline int console_getc(int file)
{
return stdio_devices[file]->getc(stdio_devices[file]);
@ -389,6 +420,9 @@ int console_start(int file, struct stdio_dev *sdev)
{
int error;
if (!console_needs_start_stop(file, sdev))
return 0;
/* Start new device */
if (sdev->start) {
error = sdev->start(sdev);
@ -401,6 +435,9 @@ int console_start(int file, struct stdio_dev *sdev)
void console_stop(int file, struct stdio_dev *sdev)
{
if (!console_needs_start_stop(file, sdev))
return;
if (sdev->stop)
sdev->stop(sdev);
}