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

Dmitry Osipenko
2020-01-16T17:38:01Z

15.01.2020 12:49, Jon Hunter пишет:
>
>
> 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@gmail.com>
>> ---
>> 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.