From a8552c7c9b53d1d4f36b95f2c80812d8a7bb4fff Mon Sep 17 00:00:00 2001 From: Hans de Goede Date: Tue, 5 May 2015 13:13:36 +0200 Subject: console: Fix pre-console flushing via cfb_console being very slow On my A10 OlinuxIno Lime I noticed a huge (5+ seconds) delay coming from console_init_r. This turns out to be caused by the preconsole buffer flushing to the cfb_console. The Lime only has a 16 bit memory bus and that is already heavy used to scan out the 1920x1080 framebuffer. The problem is that print_pre_console_buffer() was printing the buffer once character at a time and the cfb_console code then ends up doing a cache-flush for touched display lines for each character. This commit fixes this by first building a 0 terminated buffer and then printing it in one puts() call, avoiding unnecessary cache flushes. This changes the time for the flush from 5+ seconds to not noticable. The downside of this approach is that the pre-console buffer needs to fit on the stack, this is not that much to ask since we are talking about plain text here. This commit also adjusts the sunxi CONFIG_PRE_CON_BUF_SZ to actually fit on the stack. Sunxi currently is the only user of the pre-console code so no other boards need to be adjusted. Signed-off-by: Hans de Goede Reviewed-by: Tom Rini --- README | 3 +++ 1 file changed, 3 insertions(+) (limited to 'README') diff --git a/README b/README index 1ea397a35c..2e81ccc37c 100644 --- a/README +++ b/README @@ -948,6 +948,9 @@ The following options need to be configured: bytes are output before the console is initialised, the earlier bytes are discarded. + Note that when printing the buffer a copy is made on the + stack so CONFIG_PRE_CON_BUF_SZ must fit on the stack. + 'Sane' compilers will generate smaller code if CONFIG_PRE_CON_BUF_SZ is a power of 2 -- cgit v1.2.1