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Date: Fri, 3 Jun 2016 21:25:04 +0300
From: Ivan Khoronzhuk <ivan.khoronzhuk@...aro.org>
To: Grygorii Strashko <grygorii.strashko@...com>, mugunthanvnm@...com,
linux-kernel@...r.kernel.org
Cc: linux-omap@...r.kernel.org, netdev@...r.kernel.org,
robh+dt@...nel.org, pawel.moll@....com, mark.rutland@....com,
ijc+devicetree@...lion.org.uk, galak@...eaurora.org,
bcousson@...libre.com, tony@...mide.com, devicetree@...r.kernel.org
Subject: Re: [PATCH] net: ethernet: ti: cpsw: remove rx_descs property
On 03.06.16 19:50, Grygorii Strashko wrote:
> On 06/03/2016 01:43 AM, Ivan Khoronzhuk wrote:
>> There is no reason to hold s/w dependent parameter in device tree.
>> Even more, there is no reason in this parameter because davinici_cpdma
>> driver splits pool of descriptors equally between tx and rx channels.
>> That is, if number of descriptors 256, 128 of them are for rx
>> channels. While receiving, the descriptor is freed to the pool and
>> then allocated with new skb. And if in DT the "rx_descs" is set to
>> 64, then 128 - 64 = 64 descriptors are always in the pool and cannot
>> be used, for tx, for instance. It's not correct resource usage,
>> better to set it to half of pool, then the rx pool can be used in
>> full. It will not have any impact on performance, as anyway, the
>> "redundant" descriptors were unused.
>>
>> Signed-off-by: Ivan Khoronzhuk <ivan.khoronzhuk@...aro.org>
>> ---
>>
>> Based on master
>>
>> Documentation/devicetree/bindings/net/cpsw.txt | 3 ---
>> arch/arm/boot/dts/am33xx.dtsi | 1 -
>> arch/arm/boot/dts/am4372.dtsi | 1 -
>> arch/arm/boot/dts/dm814x.dtsi | 1 -
>> arch/arm/boot/dts/dra7.dtsi | 1 -
>
>
> Pls, split DT and non-DT changes, seems code changes should go first.
Ok.
>
>> drivers/net/ethernet/ti/cpsw.c | 13 +++----------
>> drivers/net/ethernet/ti/cpsw.h | 1 -
>> drivers/net/ethernet/ti/davinci_cpdma.c | 6 ++++++
>> drivers/net/ethernet/ti/davinci_cpdma.h | 1 +
>> 9 files changed, 10 insertions(+), 18 deletions(-)
>>
>> diff --git a/Documentation/devicetree/bindings/net/cpsw.txt b/Documentation/devicetree/bindings/net/cpsw.txt
>> index 0ae0649..5fe6239 100644
>> --- a/Documentation/devicetree/bindings/net/cpsw.txt
>> +++ b/Documentation/devicetree/bindings/net/cpsw.txt
>> @@ -15,7 +15,6 @@ Required properties:
>> - cpdma_channels : Specifies number of channels in CPDMA
>> - ale_entries : Specifies No of entries ALE can hold
>> - bd_ram_size : Specifies internal descriptor RAM size
>> -- rx_descs : Specifies number of Rx descriptors
>> - mac_control : Specifies Default MAC control register content
>> for the specific platform
>> - slaves : Specifies number for slaves
>> @@ -70,7 +69,6 @@ Examples:
>
> [....]
>
>> slaves = <2>;
>> active_slave = <0>;
>> diff --git a/drivers/net/ethernet/ti/cpsw.c b/drivers/net/ethernet/ti/cpsw.c
>> index 4b08a2f..635be3e 100644
>> --- a/drivers/net/ethernet/ti/cpsw.c
>> +++ b/drivers/net/ethernet/ti/cpsw.c
>> @@ -1277,6 +1277,7 @@ static int cpsw_ndo_open(struct net_device *ndev)
>> ALE_ALL_PORTS, ALE_ALL_PORTS, 0, 0);
>>
>> if (!cpsw_common_res_usage_state(priv)) {
>> + int buf_num;
>> struct cpsw_priv *priv_sl0 = cpsw_get_slave_priv(priv, 0);
>>
>> /* setup tx dma to fixed prio and zero offset */
>> @@ -1305,10 +1306,8 @@ static int cpsw_ndo_open(struct net_device *ndev)
>> enable_irq(priv->irqs_table[0]);
>> }
>>
>> - if (WARN_ON(!priv->data.rx_descs))
>> - priv->data.rx_descs = 128;
>> -
>> - for (i = 0; i < priv->data.rx_descs; i++) {
>> + buf_num = cpdma_chan_get_buf_num(priv->dma) / 2;
>
> Could you get rid of "/ 2", pls?
>
Why? compiler is smart enough to translate it to shift.
And this is not time critical place.
Anyway, will change it to >> 1 while splitting.
>> + for (i = 0; i < buf_num; i++) {
>> struct sk_buff *skb;
>>
>> ret = -ENOMEM;
>> @@ -1999,12 +1998,6 @@ static int cpsw_probe_dt(struct cpsw_platform_data *data,
>> }
>> data->bd_ram_size = prop;
>>
>> - if (of_property_read_u32(node, "rx_descs", &prop)) {
>> - dev_err(&pdev->dev, "Missing rx_descs property in the DT.\n");
>> - return -EINVAL;
>> - }
>> - data->rx_descs = prop;
>> -
>> if (of_property_read_u32(node, "mac_control", &prop)) {
>> dev_err(&pdev->dev, "Missing mac_control property in the DT.\n");
>> return -EINVAL;
>> diff --git a/drivers/net/ethernet/ti/cpsw.h b/drivers/net/ethernet/ti/cpsw.h
>> index e50afd1..16b54c6 100644
>> --- a/drivers/net/ethernet/ti/cpsw.h
>> +++ b/drivers/net/ethernet/ti/cpsw.h
>> @@ -35,7 +35,6 @@ struct cpsw_platform_data {
>> u32 cpts_clock_shift; /* convert input clock ticks to nanoseconds */
>> u32 ale_entries; /* ale table size */
>> u32 bd_ram_size; /*buffer descriptor ram size */
>> - u32 rx_descs; /* Number of Rx Descriptios */
>> u32 mac_control; /* Mac control register */
>> u16 default_vlan; /* Def VLAN for ALE lookup in VLAN aware mode*/
>> bool dual_emac; /* Enable Dual EMAC mode */
>> diff --git a/drivers/net/ethernet/ti/davinci_cpdma.c b/drivers/net/ethernet/ti/davinci_cpdma.c
>> index 18bf3a8..395647c 100644
>> --- a/drivers/net/ethernet/ti/davinci_cpdma.c
>> +++ b/drivers/net/ethernet/ti/davinci_cpdma.c
>> @@ -543,6 +543,12 @@ struct cpdma_chan *cpdma_chan_create(struct cpdma_ctlr *ctlr, int chan_num,
>> }
>> EXPORT_SYMBOL_GPL(cpdma_chan_create);
>>
>> +int cpdma_chan_get_buf_num(struct cpdma_ctlr *ctlr)
>> +{
>> + return ctlr->pool->num_desc;
>> +}
>> +EXPORT_SYMBOL_GPL(cpdma_chan_get_buf_num);
>> +
>> int cpdma_chan_destroy(struct cpdma_chan *chan)
>> {
>> struct cpdma_ctlr *ctlr;
>> diff --git a/drivers/net/ethernet/ti/davinci_cpdma.h b/drivers/net/ethernet/ti/davinci_cpdma.h
>> index 86dee48..f059856 100644
>> --- a/drivers/net/ethernet/ti/davinci_cpdma.h
>> +++ b/drivers/net/ethernet/ti/davinci_cpdma.h
>> @@ -81,6 +81,7 @@ int cpdma_ctlr_dump(struct cpdma_ctlr *ctlr);
>>
>> struct cpdma_chan *cpdma_chan_create(struct cpdma_ctlr *ctlr, int chan_num,
>> cpdma_handler_fn handler);
>> +int cpdma_chan_get_buf_num(struct cpdma_ctlr *ctlr);
>> int cpdma_chan_destroy(struct cpdma_chan *chan);
>> int cpdma_chan_start(struct cpdma_chan *chan);
>> int cpdma_chan_stop(struct cpdma_chan *chan);
>>
>
>
--
Regards,
Ivan Khoronzhuk
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