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imx233: workaround hardware dma bug

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This bug mostly affects the ZEN and ZEN X-Fi and hangs the lcdif dma randomly
on boot.

Change-Id: I4255db90d87737b7a70d1d53e3ef84e4e14c8c13
This commit is contained in:
Amaury Pouly 2016-12-12 11:31:31 +01:00 • committed by Gerrit Rockbox
parent ed6526404f
commit 42e54c508f
1 changed files with 34 additions and 0 deletions
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34
firmware/target/arm/imx233/dma-imx233.c
View file

@ -32,8 +32,42 @@
// statistics about unaligned transfers
static int apb_nr_unaligned[32];
static void safe_reset_channel(int chan)
{
bool apbx_running = !BF_RD(APBX_CTRL0, SFTRST) && !BF_RD(APBX_CTRL0, CLKGATE);
bool apbh_running = !BF_RD(APBH_CTRL0, SFTRST) && !BF_RD(APBH_CTRL0, CLKGATE);
if(APB_IS_APBX_CHANNEL(chan))
{
if(!apbx_running)
return; /* don't reset if block is not running */
}
else
{
if(!apbh_running)
return; /* don't reset if block is not running */
if(BF_RD(APBH_CTRL0, CLKGATE_CHANNEL) & (1 << chan))
return; /* don't reset a gated channel */
}
imx233_dma_reset_channel(chan);
}
void imx233_dma_init(void)
{
/* BUG The stmp3700 (and probably stmp3780) have a hardware bug related to
* resetting the block when channel is running. It appears that at least
* for the LCDIF channel, resetting the block while the channel is running
* will make the channel hang. Once the channel hang, it cannot be recovered
* except by a chip reset. On most devices this situation will never arise
* but on the Creative ZEN (X-Fi), the OF bootloader leaves the channel
* running (to display the logo) when booting. It is unclear if this bug only
* affects the APBH or also the APBX. I believe it is related to the errata about
* channels not clearing the fifo on abrupt termination which affects both
* dma engines. Also note that we can't safely reset 'all' the channels by
* setting the reset mask to 0xffff since non-implemented channels don't clear
* their reset bit... Also reset won't work on gated channels and won't work if
* block is in reset or gated, in which case this situation is assumed not
* to exists */
safe_reset_channel(APB_LCDIF);
/* Enable APHB and APBX */
imx233_reset_block(&HW_APBH_CTRL0);
imx233_reset_block(&HW_APBX_CTRL0);