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Message-ID: <CAKohpok=nv2XnFdPkD_yJgUsDqx2gEh=mG_Xhbe-BvT7swVsyg@mail.gmail.com>
Date: Fri, 12 Oct 2012 19:36:55 +0530
From: Viresh Kumar <viresh.kumar@...aro.org>
To: "Shevchenko, Andriy" <andriy.shevchenko@...el.com>
Cc: "Koul, Vinod" <vinod.koul@...el.com>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"spear-devel@...t.st.com" <spear-devel@...t.st.com>,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>,
devicetree-discuss <devicetree-discuss@...ts.ozlabs.org>
Subject: Re: [PATCH 2/3] dmaengine: dw_dmac: Enhance device tree support
On 12 October 2012 18:58, Shevchenko, Andriy
<andriy.shevchenko@...el.com> wrote:
> On Fri, 2012-10-12 at 11:14 +0530, Viresh Kumar wrote:
>> + if (!of_property_read_u32(np, "chan_allocation_order",
>> + &val))
> Fits one line?
yes.
>> + pdata->chan_allocation_order = (unsigned char)val;
> do we really need explicit casting here?
Obviously not, bigger to smaller is automatically casted. My coding standard is
going down :(
Same for all casting comments.
>> + if (!of_property_read_u32(np, "nr_masters", &val)) {
>> + if (val > 4)
> I thought once that we might introduce constant like #define
> DW_MAX_AHB_MASTERS 4. It seems a bit useless because hw is designed for
> that number anyway, but maybe you have another opinion.
Not everyone have four masters in there SoC configurations. So its better
to export correct values.
>> + if (!of_property_read_u32_array(np, "data_width", arr,
>> + pdata->nr_masters))
>> + for (count = 0; count < pdata->nr_masters; count++)
>> + pdata->data_width[count] = arr[count];
> Ah, it would be nice to have of_property_read_u8_array and so on...
:)
Maybe yes. I don't want to do it with this patchset, as that will take more
time to go through maintainers.
>> + /* calculate number of slaves */
>> + for_each_child_of_node(sn, cn)
>> + count++;
>
> of.h: static inline int of_get_child_count(const struct device_node *np)
Hehe.. Will use that.
This proves there is no efficient way of finding child nodes, than this.
>> + for_each_child_of_node(sn, cn) {
>> + of_property_read_string(cn, "bus_id", &sd[count].bus_id);
>> + of_property_read_u32(cn, "cfg_hi", &sd[count].cfg_hi);
>> + of_property_read_u32(cn, "cfg_lo", &sd[count].cfg_lo);
>> + if (!of_property_read_u32(cn, "src_master", &val))
>> + sd[count].src_master = (u8)val;
>> +
>> + if (!of_property_read_u32(cn, "dst_master", &val))
>> + sd[count].dst_master = (u8)val;
>> +
>> + sd[count].dma_dev = &pdev->dev;
>> + count++;
>> + }
>
> what about to define sd as sd[0]; in the platform_data structure and
> then use smth like following
>
> struct ... *sd = pdata->sd;
> for_each... {
> sd->... = ;
> sd++;
> }
>
> it will probably require to split this part in a separate function and
> calculate count of slave_info children before pdata memory allocation.
Liked the idea partially. Check my new implementation in fixup for all
these comments:
---------------------------8<---------------------------
From: Viresh Kumar <viresh.kumar@...aro.org>
Date: Fri, 12 Oct 2012 19:35:44 +0530
Subject: [PATCH] fixup! dmaengine: dw_dmac: Enhance device tree support
---
drivers/dma/dw_dmac.c | 50 ++++++++++++++++++++++---------------------------
include/linux/dw_dmac.h | 2 +-
2 files changed, 23 insertions(+), 29 deletions(-)
diff --git a/drivers/dma/dw_dmac.c b/drivers/dma/dw_dmac.c
index c24859e..d72c26f 100644
--- a/drivers/dma/dw_dmac.c
+++ b/drivers/dma/dw_dmac.c
@@ -1179,7 +1179,7 @@ static void dwc_free_chan_resources(struct dma_chan *chan)
dev_vdbg(chan2dev(chan), "%s: done\n", __func__);
}
-bool dw_generic_filter(struct dma_chan *chan, void *param)
+bool dw_dma_generic_filter(struct dma_chan *chan, void *param)
{
struct dw_dma *dw = to_dw_dma(chan->device);
static struct dw_dma *last_dw;
@@ -1224,7 +1224,7 @@ bool dw_generic_filter(struct dma_chan *chan, void *param)
last_bus_id = param;
return false;
}
-EXPORT_SYMBOL(dw_generic_filter);
+EXPORT_SYMBOL(dw_dma_generic_filter);
/* --------------------- Cyclic DMA API extensions -------------------- */
@@ -1516,7 +1516,7 @@ __devinit dw_dma_parse_dt(struct platform_device *pdev)
struct device_node *sn, *cn, *np = pdev->dev.of_node;
struct dw_dma_platform_data *pdata;
struct dw_dma_slave *sd;
- u32 count, val, arr[4];
+ u32 val, arr[4];
if (!np) {
dev_err(&pdev->dev, "Missing DT data\n");
@@ -1533,63 +1533,57 @@ __devinit dw_dma_parse_dt(struct platform_device *pdev)
if (of_property_read_bool(np, "is_private"))
pdata->is_private = true;
- if (!of_property_read_u32(np, "chan_allocation_order",
- &val))
+ if (!of_property_read_u32(np, "chan_allocation_order", &val))
pdata->chan_allocation_order = (unsigned char)val;
if (!of_property_read_u32(np, "chan_priority", &val))
- pdata->chan_priority = (unsigned char)val;
+ pdata->chan_priority = val;
if (!of_property_read_u32(np, "block_size", &val))
- pdata->block_size = (unsigned short)val;
+ pdata->block_size = val;
if (!of_property_read_u32(np, "nr_masters", &val)) {
if (val > 4)
return NULL;
- pdata->nr_masters = (unsigned char)val;
+ pdata->nr_masters = val;
}
if (!of_property_read_u32_array(np, "data_width", arr,
pdata->nr_masters))
- for (count = 0; count < pdata->nr_masters; count++)
- pdata->data_width[count] = arr[count];
+ for (val = 0; val < pdata->nr_masters; val++)
+ pdata->data_width[val] = arr[val];
/* parse slave data */
sn = of_find_node_by_name(np, "slave_info");
if (!sn)
return pdata;
- count = 0;
/* calculate number of slaves */
- for_each_child_of_node(sn, cn)
- count++;
-
- if (!count)
+ val = of_get_child_count(sn);
+ if (!val)
return NULL;
- sd = devm_kzalloc(&pdev->dev, sizeof(*sd) * count, GFP_KERNEL);
+ sd = devm_kzalloc(&pdev->dev, sizeof(*sd) * val, GFP_KERNEL);
if (!sd)
return NULL;
- count = 0;
+ pdata->sd = sd;
+ pdata->sd_count = val;
+
for_each_child_of_node(sn, cn) {
- of_property_read_string(cn, "bus_id", &sd[count].bus_id);
- of_property_read_u32(cn, "cfg_hi", &sd[count].cfg_hi);
- of_property_read_u32(cn, "cfg_lo", &sd[count].cfg_lo);
+ sd->dma_dev = &pdev->dev;
+ of_property_read_string(cn, "bus_id", &sd->bus_id);
+ of_property_read_u32(cn, "cfg_hi", &sd->cfg_hi);
+ of_property_read_u32(cn, "cfg_lo", &sd->cfg_lo);
if (!of_property_read_u32(cn, "src_master", &val))
- sd[count].src_master = (u8)val;
+ sd->src_master = val;
if (!of_property_read_u32(cn, "dst_master", &val))
- sd[count].dst_master = (u8)val;
-
- sd[count].dma_dev = &pdev->dev;
- count++;
+ sd->dst_master = val;
+ sd++;
}
- pdata->sd = sd;
- pdata->sd_count = count;
-
return pdata;
}
#else
diff --git a/include/linux/dw_dmac.h b/include/linux/dw_dmac.h
index 4d1c8c3..41766de 100644
--- a/include/linux/dw_dmac.h
+++ b/include/linux/dw_dmac.h
@@ -114,6 +114,6 @@ void dw_dma_cyclic_stop(struct dma_chan *chan);
dma_addr_t dw_dma_get_src_addr(struct dma_chan *chan);
dma_addr_t dw_dma_get_dst_addr(struct dma_chan *chan);
-bool dw_generic_filter(struct dma_chan *chan, void *param);
+bool dw_dma_generic_filter(struct dma_chan *chan, void *param);
#endif /* DW_DMAC_H */
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