From: Icenowy Zheng <uwu@icenowy.me>
Date: Fri, 20 May 2022 12:42:00 +0000 (+0800)
Subject: hw/sd/allwinner-sdhost: report FIFO water level as 1 when data ready
X-Git-Tag: v7.1.0-rc0~83^2~114
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=fd71f258bc0d245b2223bf3032c0ebc82f8a3463;p=thirdparty%2Fqemu.git

hw/sd/allwinner-sdhost: report FIFO water level as 1 when data ready

U-Boot queries the FIFO water level to reduce checking status register
when doing PIO SD card operation.

Report a FIFO water level of 1 when data is ready, to prevent the code
from trying to read 0 words from the FIFO each time.

Signed-off-by: Icenowy Zheng <uwu@icenowy.me>
Message-id: 20220520124200.2112699-1-uwu@icenowy.me
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---

diff --git a/hw/sd/allwinner-sdhost.c b/hw/sd/allwinner-sdhost.c
index 041e45c6804..455d6eabf64 100644
--- a/hw/sd/allwinner-sdhost.c
+++ b/hw/sd/allwinner-sdhost.c
@@ -114,7 +114,9 @@ enum {
 };
 
 enum {
+    SD_STAR_FIFO_EMPTY      = (1 << 2),
     SD_STAR_CARD_PRESENT    = (1 << 8),
+    SD_STAR_FIFO_LEVEL_1    = (1 << 17),
 };
 
 enum {
@@ -467,6 +469,11 @@ static uint64_t allwinner_sdhost_read(void *opaque, hwaddr offset,
         break;
     case REG_SD_STAR:      /* Status */
         res = s->status;
+        if (sdbus_data_ready(&s->sdbus)) {
+            res |= SD_STAR_FIFO_LEVEL_1;
+        } else {
+            res |= SD_STAR_FIFO_EMPTY;
+        }
         break;
     case REG_SD_FWLR:      /* FIFO Water Level */
         res = s->fifo_wlevel;