From mboxrd@z Thu Jan  1 00:00:00 1970
From: Stefan Mavrodiev <stefan@olimex.com>
Date: Thu, 13 Dec 2018 09:12:57 +0200
Subject: [U-Boot] [PATCH 1/1] arm: sunxi: Add NULL pointer check
In-Reply-To: <9458ed1f-38de-6be0-8e27-a2d6801492a2@gmail.com>
References: <20181205122757.14523-1-stefan@olimex.com>
 <20181205154619.ffzfl7yt6vfo3qra@flea>
 <9458ed1f-38de-6be0-8e27-a2d6801492a2@gmail.com>
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On 12/6/18 8:41 AM, Stefan Mavrodiev wrote:
>
> On 12/5/18 5:46 PM, Maxime Ripard wrote:
>> On Wed, Dec 05, 2018 at 02:27:57PM +0200, Stefan Mavrodiev wrote:
>>> Current driver doesn't check if the destination pointer is NULL.
>>> This cause the data from the FIFO to be stored inside the internal
>>> SDRAM ( address 0 ).
>>>
>>> The patch add simple check if the destination pointer is NULL.
>>>
>>> Signed-off-by: Stefan Mavrodiev <stefan@olimex.com>
>>> ---
>>>   drivers/spi/sun4i_spi.c | 3 ++-
>>>   1 file changed, 2 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/spi/sun4i_spi.c b/drivers/spi/sun4i_spi.c
>>> index b86b5a00ad..38cc743c61 100644
>>> --- a/drivers/spi/sun4i_spi.c
>>> +++ b/drivers/spi/sun4i_spi.c
>>> @@ -129,7 +129,8 @@ static inline void sun4i_spi_drain_fifo(struct 
>>> sun4i_spi_priv *priv, int len)
>>>         while (len--) {
>>>           byte = readb(&priv->regs->rxdata);
>>> -        *priv->rx_buf++ = byte;
>>> +        if (priv->rx_buf)
>>> +            *priv->rx_buf++ = byte;
>> It seems pretty inefficient to test the pointer at each access, it
>> would be better to check it once before starting the transfer.
>>
>> I'm not sure if that can even happen?
>
> I've tried to check that before draining the receive fifo, but then 
> the controller doesn't
> work. I'm thinking that the fifo must be drained in any case.
>
>>
>> Maxime
>>
Any further comments?