Re: [U-Boot] [PATCH v2 1/5] spi, spi_mxc: do not hang in spi_xchg_single

Hello Jagan,

Am 12.07.2014 14:54, schrieb Jagan Teki:

On Sat, Jul 12, 2014 at 9:40 AM, Heiko Schocherhs@denx.de wrote:

...

if status register do never set MXC_CSPICTRL_TC, spi_xchg_single endless loops. Add a timeout here to prevent endless hang.

Signed-off-by: Heiko Schocherhs@denx.de Cc: Dirk Behmedirk.behme@gmail.com Cc: Jagannadha Sutradharudu Tekijagannadh.teki@gmail.com

---

• changes for v2:
  • use timer api to poll till TC bit is set as Jagan Teki suggested and make this timeout configurable through CONFIG_SYS_SPI_MXC_WAIT

[...]

...

diff --git a/drivers/spi/mxc_spi.c b/drivers/spi/mxc_spi.c index f3f029d..4732850 100644 --- a/drivers/spi/mxc_spi.c +++ b/drivers/spi/mxc_spi.c @@ -30,6 +30,10 @@ static unsigned long spi_bases[] = { #define reg_read readl #define reg_write(a, v) writel(v, a)

+#if !defined(CONFIG_SYS_SPI_MXC_WAIT) +#define CONFIG_SYS_SPI_MXC_WAIT (CONFIG_SYS_HZ/100) /* 10 ms */ +#endif

• struct mxc_spi_slave { struct spi_slave slave; unsigned long base;

@@ -212,6 +216,8 @@ int spi_xchg_single(struct spi_slave *slave, unsigned int bitlen, int nbytes = DIV_ROUND_UP(bitlen, 8); u32 data, cnt, i; struct cspi_regs *regs = (struct cspi_regs *)mxcs->base;

•   u32 ts;
  

•   int status;
  
     debug("%s: bitlen %d dout 0x%x din 0x%x\n",
             __func__, bitlen, (u32)dout, (u32)din);
  

@@ -272,9 +278,17 @@ int spi_xchg_single(struct spi_slave *slave, unsigned int bitlen, reg_write(&regs->ctrl, mxcs->ctrl_reg | MXC_CSPICTRL_EN | MXC_CSPICTRL_XCH);

•   ts = get_timer(0);
  

•   status = reg_read(&regs->stat);
     /* Wait until the TC (Transfer completed) bit is set */
  

•   while ((reg_read(&regs->stat)&  MXC_CSPICTRL_TC) == 0)
  

•           ;
  

•   while ((status&  MXC_CSPICTRL_TC) == 0) {
  

•           if (get_timer(ts)>  CONFIG_SYS_SPI_MXC_WAIT) {
  

•                   printf("spi_xchg_single: Timeout!\n");
  

•                   return -1;
  

•           }
  

•           udelay(10);
  

Why you still used explicit delay here, get_timer will do the job finite delay right?

Yes, thats right. Good catch, thanks.

bye, Heiko