Re: [PATCH 09/13] dma/xlnx-zdma: Remove redundant statement in zdma_write_dst()

[Philippe Mathieu-Daudé]

On 2/25/20 11:01 AM, Chenqun (kuhn) wrote:
> > -----Original Message-----
> > From: Philippe Mathieu-Daudé [mailto:address@hidden]
> > Sent: Tuesday, February 25, 2020 5:36 PM
> > To: Chenqun (kuhn) <address@hidden>; qemu-
> > address@hidden; address@hidden
> > Cc: address@hidden; Zhanghailiang
> > <address@hidden>; Alistair Francis <address@hidden>;
> > address@hidden
> > Subject: Re: [PATCH 09/13] dma/xlnx-zdma: Remove redundant statement in
> > zdma_write_dst()
> >
> > On 2/25/20 3:09 AM, address@hidden wrote:
> > > From: Chen Qun <address@hidden>
> > >
> > > Clang static code analyzer show warning:
> > > hw/dma/xlnx-zdma.c:399:13: warning: Value stored to 'dst_type' is never
> > read
> > >               dst_type = FIELD_EX32(s->dsc_dst.words[3],
> > ZDMA_CH_DST_DSCR_WORD3,
> > >               ^
> > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > > Reported-by: Euler Robot <address@hidden>
> > > Signed-off-by: Chen Qun <address@hidden>
> > > ---
> > > Cc: Alistair Francis <address@hidden>
> > > Cc: "Edgar E. Iglesias" <address@hidden>
> > > Cc: Peter Maydell <address@hidden>
> > > Cc: address@hidden
> > > ---
> > >    hw/dma/xlnx-zdma.c | 2 --
> > >    1 file changed, 2 deletions(-)
> > >
> > > diff --git a/hw/dma/xlnx-zdma.c b/hw/dma/xlnx-zdma.c index
> > > 8fb83f5b07..45355c5d59 100644
> > > --- a/hw/dma/xlnx-zdma.c
> > > +++ b/hw/dma/xlnx-zdma.c
> > > @@ -396,8 +396,6 @@ static void zdma_write_dst(XlnxZDMA *s, uint8_t
> > *buf, uint32_t len)
> > >                zdma_load_descriptor(s, next, &s->dsc_dst);
> > >                dst_size = FIELD_EX32(s->dsc_dst.words[2],
> > ZDMA_CH_DST_DSCR_WORD2,
> > >                                      SIZE);
> > > -            dst_type = FIELD_EX32(s->dsc_dst.words[3],
> > ZDMA_CH_DST_DSCR_WORD3,
> > > -                                  TYPE);
> >
> > Maybe move dst_type to this if() statement now?
> Sorry, I don't follow you.   I didn't find where I could move dst_type.
> Do you mean to move the first dst_type to the if().
> Modify it like this:
>      while (len) {
>          dst_size = FIELD_EX32(s->dsc_dst.words[2], ZDMA_CH_DST_DSCR_WORD2,
>                                SIZE);
>          if (dst_size == 0 && ptype == PT_MEM) {
>              uint64_t next;
>              dst_type = FIELD_EX32(s->dsc_dst.words[3], ZDMA_CH_DST_DSCR_WORD3,
>                                TYPE);
>              next = zdma_update_descr_addr(s, dst_type,
>                                            R_ZDMA_CH_DST_CUR_DSCR_LSB);
>              zdma_load_descriptor(s, next, &s->dsc_dst);
>              dst_size = FIELD_EX32(s->dsc_dst.words[2], ZDMA_CH_DST_DSCR_WORD2,
>                                    SIZE);
>          }
>         ...
>     }

No, like this:

-- >8 --
@@ -373,7 +373,7 @@ static uint64_t zdma_update_descr_addr(XlnxZDMA *s, 
bool type,
 static void zdma_write_dst(XlnxZDMA *s, uint8_t *buf, uint32_t len)
 {
     uint32_t dst_size, dlen;
-    bool dst_intr, dst_type;
+    bool dst_intr;
     unsigned int ptype = ARRAY_FIELD_EX32(s->regs, ZDMA_CH_CTRL0, 
POINT_TYPE);
     unsigned int rw_mode = ARRAY_FIELD_EX32(s->regs, ZDMA_CH_CTRL0, MODE);
     unsigned int burst_type = ARRAY_FIELD_EX32(s->regs, ZDMA_CH_DATA_ATTR,
@@ -387,17 +387,17 @@ static void zdma_write_dst(XlnxZDMA *s, uint8_t 
*buf, uint32_t len)
     while (len) {
         dst_size = FIELD_EX32(s->dsc_dst.words[2], ZDMA_CH_DST_DSCR_WORD2,
                               SIZE);
-        dst_type = FIELD_EX32(s->dsc_dst.words[3], ZDMA_CH_DST_DSCR_WORD3,
-                              TYPE);
         if (dst_size == 0 && ptype == PT_MEM) {
             uint64_t next;
+            bool dst_type;
+
+            dst_type = FIELD_EX32(s->dsc_dst.words[3], 
ZDMA_CH_DST_DSCR_WORD3,
+                                  TYPE);
             next = zdma_update_descr_addr(s, dst_type,
                                           R_ZDMA_CH_DST_CUR_DSCR_LSB);
             zdma_load_descriptor(s, next, &s->dsc_dst);
             dst_size = FIELD_EX32(s->dsc_dst.words[2], 
ZDMA_CH_DST_DSCR_WORD2,
                                   SIZE);
-            dst_type = FIELD_EX32(s->dsc_dst.words[3], 
ZDMA_CH_DST_DSCR_WORD3,
-                                  TYPE);
         }
---