Re: [PATCH u-boot-marvell 3/5] tools: kwboot: Increase delay after changing baudrate in ARM code

[Stefan Roese]

On 27.10.21 20:57, Marek Behún wrote:

From: Pali Rohár 

Increase loop cycles from 60 to 2998272, which should increase delay
from 1ms to about 5ms on 1200 MHz CPU.

The Number 2998272 was chosen as the nearest value around 300 which can
be encoded into one ARM mov instruction. It avoids usage of movt instruction
which is not supported by ARMv5te cores.

Signed-off-by: Pali Rohár 
Reviewed-by: Marek Behún 


Reviewed-by: Stefan Roese 

Thanks,
Stefan


---
  tools/kwboot.c | 18 +-
  1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/tools/kwboot.c b/tools/kwboot.c
index a6bfd3d4ce..84294cadfe 100644
--- a/tools/kwboot.c
+++ b/tools/kwboot.c
@@ -119,7 +119,7 @@ static unsigned char kwboot_baud_code[] = {
/* ;   writel(UART_BASE + DLL, new_dll);  */
/* ;   writel(UART_BASE + DLH, new_dlh);  */
/* ;   writel(UART_BASE + LCR, lcr & ~DLAB);  */
-   /* ;   msleep(1); */
+   /* ;   msleep(5); */
/* ;   return 0;  */
/* ; }*/
  
@@ -130,7 +130,7 @@ static unsigned char kwboot_baud_code[] = {

0x01, 0x00, 0x4d, 0xe3, /* movt  r0, #0xd001  */
  
  /*  ; r2 = address of preamble string */

-   0xd0, 0x20, 0x8f, 0xe2, /* adr   r2, preamble */
+   0xcc, 0x20, 0x8f, 0xe2, /* adr   r2, preamble */
  
  /*  ; Send preamble string over UART  */

/* .Lloop_preamble:   */
@@ -177,15 +177,15 @@ static unsigned char kwboot_baud_code[] = {
  
  /*  ; Read old baudrate value */

/*  ; r2 = old_baudrate   */
-   0x8c, 0x20, 0x9f, 0xe5, /* ldr   r2, old_baudrate */
+   0x88, 0x20, 0x9f, 0xe5, /* ldr   r2, old_baudrate */
  
  /*  ; Calculate base clock*/

/*  ; r1 = r2 * r1*/
0x92, 0x01, 0x01, 0xe0, /* mul   r1, r2, r1   */
  
  /*  ; Read new baudrate value */

-   /*  ; r2 = baudrate   */
-   0x88, 0x20, 0x9f, 0xe5, /* ldr   r2, baudrate */
+   /*  ; r2 = new_baudrate   */
+   0x84, 0x20, 0x9f, 0xe5, /* ldr   r2, new_baudrate */
  
  /*  ; Calculate new Divisor Latch */

/*  ; r1 = DIV_ROUND(r1, r2) =*/
@@ -225,10 +225,10 @@ static unsigned char kwboot_baud_code[] = {
0x80, 0x10, 0xc1, 0xe3, /* bic   r1, r1, #0x80*/
0x0c, 0x10, 0x80, 0xe5, /* str   r1, [r0, #0x0c]  */
  
-/*  ; Sleep 1ms ~~ 60 cycles at 1200 MHz  */

-   /*  ; r1 = 60 */
-   0x9f, 0x1d, 0xa0, 0xe3, /* mov   r1, #0x27c0  */
-   0x09, 0x10, 0x40, 0xe3, /* movt  r1, #0x0009  */
+   /*  ; Loop 0x2dc000 (2998272) cycles  */
+   /*  ; which is about 5ms on 1200 MHz CPU  */
+   /*  ; r1 = 0x2dc000   */
+   0xb7, 0x19, 0xa0, 0xe3, /* mov   r1, #0x2dc000*/
/* .Lloop_sleep:  */
0x01, 0x10, 0x41, 0xe2, /* sub   r1, r1, #1   */
0x00, 0x00, 0x51, 0xe3, /* cmp   r1, #0   */




Viele Grüße,
Stefan

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HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-51 Fax: (+49)-8142-66989-80 Email: s...@denx.de

[PATCH u-boot-marvell 3/5] tools: kwboot: Increase delay after changing baudrate in ARM code

[Marek Behún]

From: Pali Rohár 

Increase loop cycles from 60 to 2998272, which should increase delay
from 1ms to about 5ms on 1200 MHz CPU.

The Number 2998272 was chosen as the nearest value around 300 which can
be encoded into one ARM mov instruction. It avoids usage of movt instruction
which is not supported by ARMv5te cores.

Signed-off-by: Pali Rohár 
Reviewed-by: Marek Behún 
---
 tools/kwboot.c | 18 +-
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/tools/kwboot.c b/tools/kwboot.c
index a6bfd3d4ce..84294cadfe 100644
--- a/tools/kwboot.c
+++ b/tools/kwboot.c
@@ -119,7 +119,7 @@ static unsigned char kwboot_baud_code[] = {
/* ;   writel(UART_BASE + DLL, new_dll);  */
/* ;   writel(UART_BASE + DLH, new_dlh);  */
/* ;   writel(UART_BASE + LCR, lcr & ~DLAB);  */
-   /* ;   msleep(1); */
+   /* ;   msleep(5); */
/* ;   return 0;  */
/* ; }*/
 
@@ -130,7 +130,7 @@ static unsigned char kwboot_baud_code[] = {
0x01, 0x00, 0x4d, 0xe3, /* movt  r0, #0xd001  */
 
/*  ; r2 = address of preamble string */
-   0xd0, 0x20, 0x8f, 0xe2, /* adr   r2, preamble */
+   0xcc, 0x20, 0x8f, 0xe2, /* adr   r2, preamble */
 
/*  ; Send preamble string over UART  */
/* .Lloop_preamble:   */
@@ -177,15 +177,15 @@ static unsigned char kwboot_baud_code[] = {
 
/*  ; Read old baudrate value */
/*  ; r2 = old_baudrate   */
-   0x8c, 0x20, 0x9f, 0xe5, /* ldr   r2, old_baudrate */
+   0x88, 0x20, 0x9f, 0xe5, /* ldr   r2, old_baudrate */
 
/*  ; Calculate base clock*/
/*  ; r1 = r2 * r1*/
0x92, 0x01, 0x01, 0xe0, /* mul   r1, r2, r1   */
 
/*  ; Read new baudrate value */
-   /*  ; r2 = baudrate   */
-   0x88, 0x20, 0x9f, 0xe5, /* ldr   r2, baudrate */
+   /*  ; r2 = new_baudrate   */
+   0x84, 0x20, 0x9f, 0xe5, /* ldr   r2, new_baudrate */
 
/*  ; Calculate new Divisor Latch */
/*  ; r1 = DIV_ROUND(r1, r2) =*/
@@ -225,10 +225,10 @@ static unsigned char kwboot_baud_code[] = {
0x80, 0x10, 0xc1, 0xe3, /* bic   r1, r1, #0x80*/
0x0c, 0x10, 0x80, 0xe5, /* str   r1, [r0, #0x0c]  */
 
-   /*  ; Sleep 1ms ~~ 60 cycles at 1200 MHz  */
-   /*  ; r1 = 60 */
-   0x9f, 0x1d, 0xa0, 0xe3, /* mov   r1, #0x27c0  */
-   0x09, 0x10, 0x40, 0xe3, /* movt  r1, #0x0009  */
+   /*  ; Loop 0x2dc000 (2998272) cycles  */
+   /*  ; which is about 5ms on 1200 MHz CPU  */
+   /*  ; r1 = 0x2dc000   */
+   0xb7, 0x19, 0xa0, 0xe3, /* mov   r1, #0x2dc000*/
/* .Lloop_sleep:  */
0x01, 0x10, 0x41, 0xe2, /* sub   r1, r1, #1   */
0x00, 0x00, 0x51, 0xe3, /* cmp   r1, #0   */
-- 
2.32.0