Re: [PATCH v4 08/14] dmaengine: tegra-apb: Fix coding style problems

[Dmitry Osipenko]

15.01.2020 12:49, Jon Hunter ÐÐÑÐÑ:
> 
> 
> On 12/01/2020 17:30, Dmitry Osipenko wrote:
>> This patch fixes few dozens of coding style problems reported by
>> checkpatch and prettifies code where makes sense.
>>
>> Signed-off-by: Dmitry Osipenko <digetx@xxxxxxxxx>
>> ---
>>  drivers/dma/tegra20-apb-dma.c | 276 ++++++++++++++++++----------------
>>  1 file changed, 144 insertions(+), 132 deletions(-)
>>
>> diff --git a/drivers/dma/tegra20-apb-dma.c b/drivers/dma/tegra20-apb-dma.c
>> index dff21e80ffa4..7158bd3145c4 100644
>> --- a/drivers/dma/tegra20-apb-dma.c
>> +++ b/drivers/dma/tegra20-apb-dma.c
> 
> ...
> 
>> @@ -1003,20 +1014,23 @@ static void tegra_dma_prep_wcount(struct tegra_dma_channel *tdc,
>>  		ch_regs->csr |= len_field;
>>  }
>>  
>> -static struct dma_async_tx_descriptor *tegra_dma_prep_slave_sg(
>> -	struct dma_chan *dc, struct scatterlist *sgl, unsigned int sg_len,
>> -	enum dma_transfer_direction direction, unsigned long flags,
>> -	void *context)
>> +static struct dma_async_tx_descriptor *
>> +tegra_dma_prep_slave_sg(struct dma_chan *dc,
>> +			struct scatterlist *sgl,
>> +			unsigned int sg_len,
>> +			enum dma_transfer_direction direction,
>> +			unsigned long flags,
>> +			void *context)
>>  {
>>  	struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc);
>> +	struct tegra_dma_sg_req *sg_req = NULL;
>> +	u32 csr, ahb_seq, apb_ptr, apb_seq;
>> +	enum dma_slave_buswidth slave_bw;
>>  	struct tegra_dma_desc *dma_desc;
>> -	unsigned int i;
>> -	struct scatterlist *sg;
>> -	unsigned long csr, ahb_seq, apb_ptr, apb_seq;
>>  	struct list_head req_list;
>> -	struct tegra_dma_sg_req  *sg_req = NULL;
>> -	u32 burst_size;
>> -	enum dma_slave_buswidth slave_bw;
>> +	struct scatterlist *sg;
>> +	unsigned int burst_size;
>> +	unsigned int i;
> 
> This is not really consistent with the rest of the changes by having 'i'
> and 'burst_size' on separate lines.

The goal wasn't to squash everything into a single line, but to make
code more readable. In this particular case the separated lines look
better to me.

>>  
>>  	if (!tdc->config_init) {
>>  		dev_err(tdc2dev(tdc), "DMA channel is not configured\n");
>> @@ -1028,7 +1042,7 @@ static struct dma_async_tx_descriptor *tegra_dma_prep_slave_sg(
>>  	}
>>  
>>  	if (get_transfer_param(tdc, direction, &apb_ptr, &apb_seq, &csr,
>> -				&burst_size, &slave_bw) < 0)
>> +			       &burst_size, &slave_bw) < 0)
>>  		return NULL;
>>  
>>  	INIT_LIST_HEAD(&req_list);
>> @@ -1074,7 +1088,7 @@ static struct dma_async_tx_descriptor *tegra_dma_prep_slave_sg(
>>  		len = sg_dma_len(sg);
>>  
>>  		if ((len & 3) || (mem & 3) ||
>> -				(len > tdc->tdma->chip_data->max_dma_count)) {
>> +		    len > tdc->tdma->chip_data->max_dma_count) {
>>  			dev_err(tdc2dev(tdc),
>>  				"DMA length/memory address is not supported\n");
>>  			tegra_dma_desc_put(tdc, dma_desc);
>> @@ -1126,20 +1140,21 @@ static struct dma_async_tx_descriptor *tegra_dma_prep_slave_sg(
>>  	return &dma_desc->txd;
>>  }
>>  
>> -static struct dma_async_tx_descriptor *tegra_dma_prep_dma_cyclic(
>> -	struct dma_chan *dc, dma_addr_t buf_addr, size_t buf_len,
>> -	size_t period_len, enum dma_transfer_direction direction,
>> -	unsigned long flags)
>> +static struct dma_async_tx_descriptor *
>> +tegra_dma_prep_dma_cyclic(struct dma_chan *dc, dma_addr_t buf_addr,
>> +			  size_t buf_len,
>> +			  size_t period_len,
>> +			  enum dma_transfer_direction direction,
>> +			  unsigned long flags)
>>  {
>>  	struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc);
>> -	struct tegra_dma_desc *dma_desc = NULL;
>>  	struct tegra_dma_sg_req *sg_req = NULL;
>> -	unsigned long csr, ahb_seq, apb_ptr, apb_seq;
>> -	int len;
>> -	size_t remain_len;
>> -	dma_addr_t mem = buf_addr;
>> -	u32 burst_size;
>> +	u32 csr, ahb_seq, apb_ptr, apb_seq;
>>  	enum dma_slave_buswidth slave_bw;
>> +	struct tegra_dma_desc *dma_desc;
>> +	dma_addr_t mem = buf_addr;
>> +	unsigned int burst_size;
>> +	size_t len, remain_len;
>>  
>>  	if (!buf_len || !period_len) {
>>  		dev_err(tdc2dev(tdc), "Invalid buffer/period len\n");
>> @@ -1173,13 +1188,13 @@ static struct dma_async_tx_descriptor *tegra_dma_prep_dma_cyclic(
>>  
>>  	len = period_len;
>>  	if ((len & 3) || (buf_addr & 3) ||
>> -			(len > tdc->tdma->chip_data->max_dma_count)) {
>> +	    len > tdc->tdma->chip_data->max_dma_count) {
>>  		dev_err(tdc2dev(tdc), "Req len/mem address is not correct\n");
>>  		return NULL;
>>  	}
>>  
>>  	if (get_transfer_param(tdc, direction, &apb_ptr, &apb_seq, &csr,
>> -				&burst_size, &slave_bw) < 0)
>> +			       &burst_size, &slave_bw) < 0)
>>  		return NULL;
>>  
>>  	ahb_seq = TEGRA_APBDMA_AHBSEQ_INTR_ENB;
>> @@ -1269,7 +1284,6 @@ static int tegra_dma_alloc_chan_resources(struct dma_chan *dc)
>>  	int ret;
>>  
>>  	dma_cookie_init(&tdc->dma_chan);
>> -	tdc->config_init = false;
> 
> Why is this removed? Does not seem to belong in this patch.

Because initially, on driver's probe, the tdc->config_init is false for
all channels and then tegra_dma_free_chan_resources() also sets it to
false. Thus there is no need to re-initilize the already initialized
variable. It's not a very good coding style if variables are
unnecessarily initialized, you probably noticed that there are few other
cases of removing the unneeded initializations of local variables in
this patch.