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

[Chenqun (kuhn)]

>-----Original Message-----
>From: Philippe Mathieu-Daudé [mailto:address@hidden]
>Sent: Tuesday, February 25, 2020 6:12 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 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);
>          }
Hmm,  this is better. 
I will modify it later in V2.

Thanks.
>---