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liblitesdcard/sdcard: adjust card-ready timeout 

Testing on nexys4ddr and rocket, approximately 12 iterations of the
timeout loop (using `busy_wait(1)`) are needed to receive a "ready"
response from the SDcard, assuming a "warm" reset where the card has
already been previously initialized.

If the SDcard is ejected and re-inserted, or if the board is "cold-reset"
(e.g., reprogrammed via openocd vs. a simple push of the reset button),
it takes approximately 450 iterations before the SDCard responds with a
"ready" message.

In either case, a timeout of 10 is insufficient. This patch increases
the busy-wait to 10, and the timeout loop counter to 128, which should
cover most cases.

Additionally, make a few minor cosmetic improvements.

Signed-off-by: Gabriel Somlo <gsomlo@gmail.com>
This commit is contained in:
Gabriel Somlo 2020-07-06 17:00:24 -04:00
parent e473c6f29e
commit 6fdb36b84a
1 changed files with 3 additions and 5 deletions
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8
litex/soc/software/liblitesdcard/sdcard.c
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@ -448,7 +448,7 @@ void sdcard_decode_csd(void) {
int sdcard_init(void) { int sdcard_init(void) {
unsigned short rca; unsigned short rca;
uint16_t timeout; uint16_t timeout;
/* initialize freq */ /* initialize freq */
sdcard_set_clk_freq(16000000); sdcard_set_clk_freq(16000000);
@ -462,15 +462,13 @@ int sdcard_init(void) {
busy_wait(1); busy_wait(1);
sdcard_send_ext_csd(); sdcard_send_ext_csd();
/* wait for card to be ready */ /* wait for card to be ready */
timeout = 10; for (timeout = 128; timeout > 0; timeout--) {
while (timeout) {
sdcard_app_cmd(0); sdcard_app_cmd(0);
sdcard_app_send_op_cond(1, 0); sdcard_app_send_op_cond(1, 0);
if (sdcard_response[3] & 0x80000000) { if (sdcard_response[3] & 0x80000000) {
break; break;
} }
busy_wait(1); busy_wait(10);
timeout--;
} }
if (timeout == 0) if (timeout == 0)
return 0; return 0;