[Qemu-devel] [PATCH v1 0/1] xilinx_spips dummy bytes fix

[Qemu-devel] [PATCH v1 0/1] xilinx_spips dummy bytes fix

[Sai Pavan Boddu]

For zynq-7000 boards, we saw issues when u-boot/linux accessing the qspi.
Issue is due to wrong dummy byte transfers for few of un-handled commands ex: 0x9F, 0x6, 0xe9, 0x4, 0x18, etc
There are many unhandled commands which do not require dummy bytes but they can be followed by address cycles.

To fix this issue for above commands, the next upcoming tx bytes are not considered dummies rather sent to slave directly.

Sai Pavan Boddu (1):
  xilinx_spips: send dummy only if cmd requires it

 hw/ssi/xilinx_spips.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

-- 
2.7.4

[Qemu-devel] [PATCH v1 1/1] xilinx_spips: send dummy only if cmd requires it

[Sai Pavan Boddu]

For all the commands, which do not have an entry in
xilinx_spips_num_dummies, present logic sends dummy byte when ever we
are in SNOOP_NONE state, fix it to send only if cmd requires them.

Only transmit max of 1 dummy byte(i.e 8 cycles) is a single snoop cycle.
And also convert dummy bytes to cycles (required by m25p80).

Signed-off-by: Sai Pavan Boddu <saipava@xilinx.com>
---
 hw/ssi/xilinx_spips.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/hw/ssi/xilinx_spips.c b/hw/ssi/xilinx_spips.c
index 426f971..8278930 100644
--- a/hw/ssi/xilinx_spips.c
+++ b/hw/ssi/xilinx_spips.c
@@ -627,10 +627,17 @@ static void xilinx_spips_flush_txfifo(XilinxSPIPS *s)
                 tx_rx[i] = tx;
             }
         } else {
-            /* Extract a dummy byte and generate dummy cycles according to the
-             * link state */
             tx = fifo8_pop(&s->tx_fifo);
-            dummy_cycles = 8 / s->link_state;
+            if (s->cmd_dummies > 0) {
+                /* Extract a dummy byte and generate dummy cycles according to
+                 * the link state */
+                 dummy_cycles = (s->cmd_dummies ? 1 : 0) * 8 / s->link_state;
+                 s->cmd_dummies--;
+            } else {
+                for (i = 0; i < num_effective_busses(s); ++i) {
+                    tx_rx[i] = tx;
+                }
+            }
         }
 
         for (i = 0; i < num_effective_busses(s); ++i) {
-- 
2.7.4

Re: [Qemu-devel] [PATCH v1 0/1] xilinx_spips dummy bytes fix

[Alistair Francis]

On Tue, Apr 17, 2018 at 7:18 AM, Sai Pavan Boddu
<sai.pavan.boddu@xilinx.com> wrote:
> For zynq-7000 boards, we saw issues when u-boot/linux accessing the qspi.
> Issue is due to wrong dummy byte transfers for few of un-handled commands ex: 0x9F, 0x6, 0xe9, 0x4, 0x18, etc
> There are many unhandled commands which do not require dummy bytes but they can be followed by address cycles.
>
> To fix this issue for above commands, the next upcoming tx bytes are not considered dummies rather sent to slave directly.
>
> Sai Pavan Boddu (1):
>   xilinx_spips: send dummy only if cmd requires it

I don't see this patch on the list, I only see the cover letter.

Do other see it?

Alistair

>
>  hw/ssi/xilinx_spips.c | 13 ++++++++++---
>  1 file changed, 10 insertions(+), 3 deletions(-)
>
> --
> 2.7.4
>
>

Re: [Qemu-devel] [PATCH v1 0/1] xilinx_spips dummy bytes fix

[Alistair Francis]

On Tue, Apr 17, 2018 at 8:47 AM, Alistair Francis <alistair23@gmail.com> wrote:
> On Tue, Apr 17, 2018 at 7:18 AM, Sai Pavan Boddu
> <sai.pavan.boddu@xilinx.com> wrote:
>> For zynq-7000 boards, we saw issues when u-boot/linux accessing the qspi.
>> Issue is due to wrong dummy byte transfers for few of un-handled commands ex: 0x9F, 0x6, 0xe9, 0x4, 0x18, etc
>> There are many unhandled commands which do not require dummy bytes but they can be followed by address cycles.
>>
>> To fix this issue for above commands, the next upcoming tx bytes are not considered dummies rather sent to slave directly.
>>
>> Sai Pavan Boddu (1):
>>   xilinx_spips: send dummy only if cmd requires it
>
> I don't see this patch on the list, I only see the cover letter.
>
> Do other see it?

Never mind, it just came through.

Alistair

>
> Alistair
>
>>
>>  hw/ssi/xilinx_spips.c | 13 ++++++++++---
>>  1 file changed, 10 insertions(+), 3 deletions(-)
>>
>> --
>> 2.7.4
>>
>>

Re: [Qemu-devel] [PATCH v1 1/1] xilinx_spips: send dummy only if cmd requires it

[francisco iglesias]

Hi Sai,

[PATCH v1] xilinx_spips: send dummy only if cmd requires it

s/dummy/dummy cycles/

On 17 April 2018 at 16:18, Sai Pavan Boddu <sai.pavan.boddu@xilinx.com>
wrote:

> For all the commands, which do not have an entry in
> xilinx_spips_num_dummies, present logic sends dummy byte when ever we
>

s/dummy byte/dummy cycles/


> are in SNOOP_NONE state, fix it to send only if cmd requires them.
>
> s/fix it to send only if cmd/fix it to only send dummy cycles if the
command/

Only transmit max of 1 dummy byte(i.e 8 cycles) is a single snoop cycle.
> And also convert dummy bytes to cycles (required by m25p80).
>

Maybe it is better to drop this two last lines (was already done before so
it could be misleading when reading git history).


>
>
Signed-off-by: Sai Pavan Boddu <saipava@xilinx.com>
> ---
>  hw/ssi/xilinx_spips.c | 13 ++++++++++---
>  1 file changed, 10 insertions(+), 3 deletions(-)
>
> diff --git a/hw/ssi/xilinx_spips.c b/hw/ssi/xilinx_spips.c
> index 426f971..8278930 100644
> --- a/hw/ssi/xilinx_spips.c
> +++ b/hw/ssi/xilinx_spips.c
> @@ -627,10 +627,17 @@ static void xilinx_spips_flush_txfifo(XilinxSPIPS
> *s)
>                  tx_rx[i] = tx;
>              }
>          } else {
> -            /* Extract a dummy byte and generate dummy cycles according
> to the
> -             * link state */
>              tx = fifo8_pop(&s->tx_fifo);
> -            dummy_cycles = 8 / s->link_state;
> +            if (s->cmd_dummies > 0) {
> +                /* Extract a dummy byte and generate dummy cycles
> according to
> +                 * the link state */
> +                 dummy_cycles = (s->cmd_dummies ? 1 : 0) * 8 /
> s->link_state;
> +                 s->cmd_dummies--;
> +            } else {
> +                for (i = 0; i < num_effective_busses(s); ++i) {
> +                    tx_rx[i] = tx;
> +                }
> +            }
>          }
>
>
Could we replace above with below in the same if ladder so we don't
complicate the code more than necessary? (Should give the same result when
num_effective_busses == 1)

-        } else if (s->snoop_state == SNOOP_STRIPING) {
+        } else if (s->snoop_state == SNOOP_STRIPING ||
+                   s->snoop_state == SNOOP_NONE) {


Thank you!

Best regards,
Francisco Iglesias




>          for (i = 0; i < num_effective_busses(s); ++i) {
> --
> 2.7.4
>
>

Re: [Qemu-devel] [PATCH v1 1/1] xilinx_spips: send dummy only if cmd requires it

[Sai Pavan Boddu]

Hi Francisco,

From: francisco iglesias [mailto:frasse.iglesias@gmail.com]
Sent: Wednesday, April 18, 2018 4:13 AM
To: Sai Pavan Boddu <saipava@xilinx.com>
Cc: alistair@alistair23.me; crosthwaite.peter@gmail.com; Peter Maydell <peter.maydell@linaro.org>; Edde <edgar.iglesias@gmail.com>; qemu-devel@nongnu.org Developers <qemu-devel@nongnu.org>
Subject: Re: [PATCH v1 1/1] xilinx_spips: send dummy only if cmd requires it

Hi Sai,

[PATCH v1] xilinx_spips: send dummy only if cmd requires it

s/dummy/dummy cycles/

On 17 April 2018 at 16:18, Sai Pavan Boddu <sai.pavan.boddu@xilinx.com<mailto:sai.pavan.boddu@xilinx.com>> wrote:
For all the commands, which do not have an entry in
xilinx_spips_num_dummies, present logic sends dummy byte when ever we

s/dummy byte/dummy cycles/

are in SNOOP_NONE state, fix it to send only if cmd requires them.
s/fix it to send only if cmd/fix it to only send dummy cycles if the command/

Only transmit max of 1 dummy byte(i.e 8 cycles) is a single snoop cycle.
And also convert dummy bytes to cycles (required by m25p80).

Maybe it is better to drop this two last lines (was already done before so it could be misleading when reading git history).


Signed-off-by: Sai Pavan Boddu <saipava@xilinx.com<mailto:saipava@xilinx.com>>
---
 hw/ssi/xilinx_spips.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/hw/ssi/xilinx_spips.c b/hw/ssi/xilinx_spips.c
index 426f971..8278930 100644
--- a/hw/ssi/xilinx_spips.c
+++ b/hw/ssi/xilinx_spips.c
@@ -627,10 +627,17 @@ static void xilinx_spips_flush_txfifo(XilinxSPIPS *s)
                 tx_rx[i] = tx;
             }
         } else {
-            /* Extract a dummy byte and generate dummy cycles according to the
-             * link state */
             tx = fifo8_pop(&s->tx_fifo);
-            dummy_cycles = 8 / s->link_state;
+            if (s->cmd_dummies > 0) {
+                /* Extract a dummy byte and generate dummy cycles according to
+                 * the link state */
+                 dummy_cycles = (s->cmd_dummies ? 1 : 0) * 8 / s->link_state;
+                 s->cmd_dummies--;
+            } else {
+                for (i = 0; i < num_effective_busses(s); ++i) {
+                    tx_rx[i] = tx;
+                }
+            }
         }

Could we replace above with below in the same if ladder so we don't complicate the code more than necessary? (Should give the same result when num_effective_busses == 1)

-        } else if (s->snoop_state == SNOOP_STRIPING) {
+        } else if (s->snoop_state == SNOOP_STRIPING ||
+                   s->snoop_state == SNOOP_NONE) {
[Sai Pavan Boddu] Yes, this can be done. As SNOOP_NONE state is moved above, the last bottom else can be used only to issue dummy cycles. I will send V2 with above changes and commit message fixed.

Regards,
Sai Pavan


Thank you!

Best regards,
Francisco Iglesias



         for (i = 0; i < num_effective_busses(s); ++i) {
--
2.7.4