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

[Heiko Schocher <hs@denx.de>]

Hello Jagan,

Am 12.07.2014 14:54, schrieb Jagan Teki:
> On Sat, Jul 12, 2014 at 9:40 AM, Heiko Schocher<hs@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 Schocher<hs@denx.de>
>> Cc: Dirk Behme<dirk.behme@gmail.com>
>> Cc: Jagannadha Sutradharudu Teki<jagannadh.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
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