Re: [RESEND PATCH V6 1/2] i2c: i2c-qcom-geni: Store DMA mapping data in geni_i2c_dev struct

[rojay@codeaurora.org]

On 2020-12-09 18:29, Akash Asthana wrote:
> Hi Roja,
> 
> On 12/3/2020 4:01 PM, Roja Rani Yarubandi wrote:
>> Store DMA mapping data in geni_i2c_dev struct to enhance DMA mapping
>> data scope. For example during shutdown callback to unmap DMA mapping,
>> this stored DMA mapping data can be used to call geni_se_tx_dma_unprep
>> and geni_se_rx_dma_unprep functions.
>> 
>> Add two helper functions geni_i2c_rx_msg_cleanup and
>> geni_i2c_tx_msg_cleanup to unwrap the things after rx/tx FIFO/DMA
>> transfers, so that the same can be used in geni_i2c_stop_xfer()
>> function during shutdown callback.
>> 
>> Signed-off-by: Roja Rani Yarubandi <rojay@codeaurora.org>
>> ---
>> Changes in V5:
>>   - As per Stephen's comments separated this patch from shutdown
>>     callback patch, gi2c->cur = NULL is not removed from
>>     geni_i2c_abort_xfer(), and made a copy of gi2c->cur and passed
>>     to cleanup functions.
>> 
>> Changes in V6:
>>   - Added spin_lock/unlock in geni_i2c_rx_msg_cleanup() and
>>     geni_i2c_tx_msg_cleanup() functions.
>> 
>>   drivers/i2c/busses/i2c-qcom-geni.c | 69 
>> +++++++++++++++++++++++-------
>>   1 file changed, 53 insertions(+), 16 deletions(-)
>> 
>> diff --git a/drivers/i2c/busses/i2c-qcom-geni.c 
>> b/drivers/i2c/busses/i2c-qcom-geni.c
>> index dce75b85253c..bfbc80f65006 100644
>> --- a/drivers/i2c/busses/i2c-qcom-geni.c
>> +++ b/drivers/i2c/busses/i2c-qcom-geni.c
>> @@ -86,6 +86,9 @@ struct geni_i2c_dev {
>>   	u32 clk_freq_out;
>>   	const struct geni_i2c_clk_fld *clk_fld;
>>   	int suspended;
>> +	void *dma_buf;
>> +	size_t xfer_len;
>> +	dma_addr_t dma_addr;
>>   };
>>     struct geni_i2c_err_log {
>> @@ -348,14 +351,49 @@ static void geni_i2c_tx_fsm_rst(struct 
>> geni_i2c_dev *gi2c)
>>   		dev_err(gi2c->se.dev, "Timeout resetting TX_FSM\n");
>>   }
>>   +static void geni_i2c_rx_msg_cleanup(struct geni_i2c_dev *gi2c,
>> +				     struct i2c_msg *cur)
>> +{
>> +	struct geni_se *se = &gi2c->se;
>> +	unsigned long flags;
>> +
>> +	spin_lock_irqsave(&gi2c->lock, flags);
>> +	gi2c->cur_rd = 0;
>> +	if (gi2c->dma_buf) {
>> +		if (gi2c->err)
>> +			geni_i2c_rx_fsm_rst(gi2c);
> 
> Which race we are trying to avoid here by holding spinlock?
> 

Thought that race might occur with "cur" here.

> We cannot call any sleeping API by holding spinlock,
> geni_i2c_rx_fsm_rst calls *wait-for-completion*, which is a sleeping
> call.
> 

Fixed this.

>> +		geni_se_rx_dma_unprep(se, gi2c->dma_addr, gi2c->xfer_len);
>> +		i2c_put_dma_safe_msg_buf(gi2c->dma_buf, cur, !gi2c->err);
>> +	}
>> +	spin_unlock_irqrestore(&gi2c->lock, flags);
>> +}
>> +
>> +static void geni_i2c_tx_msg_cleanup(struct geni_i2c_dev *gi2c,
>> +				     struct i2c_msg *cur)
>> +{
>> +	struct geni_se *se = &gi2c->se;
>> +	unsigned long flags;
>> +
>> +	spin_lock_irqsave(&gi2c->lock, flags);
>> +	gi2c->cur_wr = 0;
>> +	if (gi2c->dma_buf) {
>> +		if (gi2c->err)
>> +			geni_i2c_tx_fsm_rst(gi2c);
> 
> Same here
> 
> Regards,
> 
> Akash
> 
>> +		geni_se_tx_dma_unprep(se, gi2c->dma_addr, gi2c->xfer_len);
>> +		i2c_put_dma_safe_msg_buf(gi2c->dma_buf, cur, !gi2c->err);
>> +	}
>> +	spin_unlock_irqrestore(&gi2c->lock, flags);
>> +}
>> +
>>   static int geni_i2c_rx_one_msg(struct geni_i2c_dev *gi2c, struct 
>> i2c_msg *msg,
>>   				u32 m_param)
>>   {
>> -	dma_addr_t rx_dma;
>> +	dma_addr_t rx_dma = 0;
>>   	unsigned long time_left;
>>   	void *dma_buf = NULL;
>>   	struct geni_se *se = &gi2c->se;
>>   	size_t len = msg->len;
>> +	struct i2c_msg *cur;
>>     	if (!of_machine_is_compatible("lenovo,yoga-c630"))
>>   		dma_buf = i2c_get_dma_safe_msg_buf(msg, 32);
>> @@ -372,19 +410,18 @@ static int geni_i2c_rx_one_msg(struct 
>> geni_i2c_dev *gi2c, struct i2c_msg *msg,
>>   		geni_se_select_mode(se, GENI_SE_FIFO);
>>   		i2c_put_dma_safe_msg_buf(dma_buf, msg, false);
>>   		dma_buf = NULL;
>> +	} else {
>> +		gi2c->xfer_len = len;
>> +		gi2c->dma_addr = rx_dma;
>> +		gi2c->dma_buf = dma_buf;
>>   	}
>>   +	cur = gi2c->cur;
>>   	time_left = wait_for_completion_timeout(&gi2c->done, XFER_TIMEOUT);
>>   	if (!time_left)
>>   		geni_i2c_abort_xfer(gi2c);
>>   -	gi2c->cur_rd = 0;
>> -	if (dma_buf) {
>> -		if (gi2c->err)
>> -			geni_i2c_rx_fsm_rst(gi2c);
>> -		geni_se_rx_dma_unprep(se, rx_dma, len);
>> -		i2c_put_dma_safe_msg_buf(dma_buf, msg, !gi2c->err);
>> -	}
>> +	geni_i2c_rx_msg_cleanup(gi2c, cur);
>>     	return gi2c->err;
>>   }
>> @@ -392,11 +429,12 @@ static int geni_i2c_rx_one_msg(struct 
>> geni_i2c_dev *gi2c, struct i2c_msg *msg,
>>   static int geni_i2c_tx_one_msg(struct geni_i2c_dev *gi2c, struct 
>> i2c_msg *msg,
>>   				u32 m_param)
>>   {
>> -	dma_addr_t tx_dma;
>> +	dma_addr_t tx_dma = 0;
>>   	unsigned long time_left;
>>   	void *dma_buf = NULL;
>>   	struct geni_se *se = &gi2c->se;
>>   	size_t len = msg->len;
>> +	struct i2c_msg *cur;
>>     	if (!of_machine_is_compatible("lenovo,yoga-c630"))
>>   		dma_buf = i2c_get_dma_safe_msg_buf(msg, 32);
>> @@ -413,22 +451,21 @@ static int geni_i2c_tx_one_msg(struct 
>> geni_i2c_dev *gi2c, struct i2c_msg *msg,
>>   		geni_se_select_mode(se, GENI_SE_FIFO);
>>   		i2c_put_dma_safe_msg_buf(dma_buf, msg, false);
>>   		dma_buf = NULL;
>> +	} else {
>> +		gi2c->xfer_len = len;
>> +		gi2c->dma_addr = tx_dma;
>> +		gi2c->dma_buf = dma_buf;
>>   	}
>>     	if (!dma_buf) /* Get FIFO IRQ */
>>   		writel_relaxed(1, se->base + SE_GENI_TX_WATERMARK_REG);
>>   +	cur = gi2c->cur;
>>   	time_left = wait_for_completion_timeout(&gi2c->done, XFER_TIMEOUT);
>>   	if (!time_left)
>>   		geni_i2c_abort_xfer(gi2c);
>>   -	gi2c->cur_wr = 0;
>> -	if (dma_buf) {
>> -		if (gi2c->err)
>> -			geni_i2c_tx_fsm_rst(gi2c);
>> -		geni_se_tx_dma_unprep(se, tx_dma, len);
>> -		i2c_put_dma_safe_msg_buf(dma_buf, msg, !gi2c->err);
>> -	}
>> +	geni_i2c_tx_msg_cleanup(gi2c, cur);
>>     	return gi2c->err;
>>   }