ASoC: loongson: Fix invalid position error in ls_pcm_pointer

The "invalid position" error occurred when the DMA position descriptor
returned an invalid address value (e.g., pos = -1048838144). This happened
because the `bytes_to_frames()` function returns a signed value, but when
`addr < runtime->dma_addr`, the subtraction produces a negative result that
gets interpreted as a large unsigned integer in comparisons.
when the addr is abnormal, for example,the DMA controller is abnormal in
hardware,x=0 should not be a point(x == runtime->buffer_size),but a range,
which includes the addr address being less than runtime ->dma1-adr, and
the addr exceeding the DMA address range.the value of pos should not better
a negative，return 0, maybe better.

[   32.834431][ 2]  soc-audio soc-audio: invalid position: , pos = -1048838144
[   32.845019][ 2]  soc-audio soc-audio: invalid position: , pos = -1048838144
[   32.855588][ 2]  soc-audio soc-audio: invalid position: , pos = -1048838144
[   32.866145][ 2]  soc-audio soc-audio: invalid position: , pos = -1048838144
[   32.995394][ 2]  soc-audio soc-audio: invalid position: , pos = -1048838144
[   33.006025][ 2]  soc-audio soc-audio: invalid position: , pos = -1048838144
[   33.016748][ 2]  soc-audio soc-audio: invalid position: , pos = -1048838144

Signed-off-by: Li Jun <lijun01@kylinos.cn>
[Remove XRUN reporting I'd mistakenly avised adding on prior review -- broonie]
Link: https://patch.msgid.link/20260611010045.3668574-1-lijun01@kylinos.cn
Signed-off-by: Mark Brown <broonie@kernel.org>

diff --git a/sound/soc/loongson/loongson_dma.c b/sound/soc/loongson/loongson_dma.c
index a149b643175c0fc7f65ef0de6e03c73d029f0229..f3ed14a48bd59bd3b45ff4f4ceceb80b99a7488f 100644 (file)
--- a/sound/soc/loongson/loongson_dma.c
+++ b/sound/soc/loongson/loongson_dma.c
@@ -199,6 +199,7 @@ loongson_pcm_pointer(struct snd_soc_component *component,
                     struct snd_pcm_substream *substream)
 {
        struct snd_pcm_runtime *runtime = substream->runtime;
+       struct device *dev = substream->pcm->card->dev;
        struct loongson_runtime_data *prtd = runtime->private_data;
        struct loongson_dma_desc *desc;
        snd_pcm_uframes_t x;
@@ -207,9 +208,16 @@ loongson_pcm_pointer(struct snd_soc_component *component,
        desc = dma_desc_save(prtd);
        addr = ((u64)desc->saddr_hi << 32) | desc->saddr;
 
-       x = bytes_to_frames(runtime, addr - runtime->dma_addr);
-       if (x == runtime->buffer_size)
+       if (addr < runtime->dma_addr ||
+           addr > runtime->dma_addr + runtime->dma_bytes) {
+               dev_warn(dev, "WARNING! dma_addr:0x%llx\n", addr);
                x = 0;
+       } else {
+               x = bytes_to_frames(runtime, addr - runtime->dma_addr);
+               if (x == runtime->buffer_size)
+                       x = 0;
+       }
+
        return x;
 }