From: Anup Patel <anup.patel@broadcom.com>
To: Vinod Koul <vinod.koul@intel.com>
Cc: Rob Herring <robh+dt@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Herbert Xu <herbert@gondor.apana.org.au>,
"David S . Miller" <davem@davemloft.net>,
Jassi Brar <jassisinghbrar@gmail.com>,
Dan Williams <dan.j.williams@intel.com>,
Ray Jui <rjui@broadcom.com>,
Scott Branden <sbranden@broadcom.com>,
Jon Mason <jonmason@broadcom.com>,
Rob Rice <rob.rice@broadcom.com>,
BCM Kernel Feedback <bcm-kernel-feedback-list@broadcom.com>,
dmaengine@vger.kernel.org,
Device Tree <devicetree@vger.kernel.org>,
Linux ARM Kernel <linux-arm-kernel@lists.infradead.org>,
Linux Kernel <linux-kernel@vger.kernel.org>,
linux-crypto@vger.kernel.org,
linux-raid <linux-raid@vger.kernel.org>
Subject: Re: [PATCH 5/6] dmaengine: Add Broadcom SBA RAID driver
Date: Tue, 7 Feb 2017 11:32:23 +0530 [thread overview]
Message-ID: <CAALAos8W13Xcxw+VpkvJWNNEiO6_6Hri0EheASHqOzCKagDYzA@mail.gmail.com> (raw)
In-Reply-To: <20170206165400.GD19244@localhost>
On Mon, Feb 6, 2017 at 10:24 PM, Vinod Koul <vinod.koul@intel.com> wrote:
> On Mon, Feb 06, 2017 at 05:31:15PM +0530, Anup Patel wrote:
>
>> >> +
>> >> +/* SBA C_MDATA helper macros */
>> >> +#define SBA_C_MDATA_LOAD_VAL(__bnum0) ((__bnum0) & 0x3)
>> >> +#define SBA_C_MDATA_WRITE_VAL(__bnum0) ((__bnum0) & 0x3)
>> >> +#define SBA_C_MDATA_XOR_VAL(__bnum1, __bnum0) \
>> >> + ({ u32 __v = ((__bnum0) & 0x3); \
>> >> + __v |= ((__bnum1) & 0x3) << 2; \
>> >> + __v; \
>> >> + })
>> >> +#define SBA_C_MDATA_PQ_VAL(__dnum, __bnum1, __bnum0) \
>> >> + ({ u32 __v = ((__bnum0) & 0x3); \
>> >> + __v |= ((__bnum1) & 0x3) << 2; \
>> >> + __v |= ((__dnum) & 0x1f) << 5; \
>> >> + __v; \
>> >> + })
>> >
>> > ah why are we usig complex macros, why can't these be simple functions..
>>
>> "static inline functions" seemed too complicated here because most of
>> these macros are two lines of c-code.
>
> and thats where I have an issue with this. Macros for simple things is fine
> but not for couple of line of logic!
>
>>
>> Do you still insist on using "static inline functions"?
>
> Yes
Sure, will use "static inline functions" instead these macros.
>
>>
>> >
>> >> +#define SBA_C_MDATA_LS(__c_mdata_val) ((__c_mdata_val) & 0xff)
>> >> +#define SBA_C_MDATA_MS(__c_mdata_val) (((__c_mdata_val) >> 8) & 0x3)
>> >> +
>> >> +/* Driver helper macros */
>> >> +#define to_sba_request(tx) \
>> >> + container_of(tx, struct sba_request, tx)
>> >> +#define to_sba_device(dchan) \
>> >> + container_of(dchan, struct sba_device, dma_chan)
>> >> +
>> >> +enum sba_request_state {
>> >> + SBA_REQUEST_STATE_FREE = 1,
>> >> + SBA_REQUEST_STATE_ALLOCED = 2,
>> >> + SBA_REQUEST_STATE_PENDING = 3,
>> >> + SBA_REQUEST_STATE_ACTIVE = 4,
>> >> + SBA_REQUEST_STATE_COMPLETED = 5,
>> >> + SBA_REQUEST_STATE_ABORTED = 6,
>> >
>> > whats up with a very funny indentation setting, we use 8 chars.
>> >
>> > Please re-read the Documentation/process/coding-style.rst
>>
>> I have double checked this enum. The indentation is fine
>> and as-per coding style. Am I missing anything else?
>
> Somehow the initial indent doesnt seem to be 8 chars to me.
>
>> >> +static enum dma_status sba_tx_status(struct dma_chan *dchan,
>> >> + dma_cookie_t cookie,
>> >> + struct dma_tx_state *txstate)
>> >> +{
>> >> + int mchan_idx;
>> >> + enum dma_status ret;
>> >> + struct sba_device *sba = to_sba_device(dchan);
>> >> +
>> >> + ret = dma_cookie_status(dchan, cookie, txstate);
>> >> + if (ret == DMA_COMPLETE)
>> >> + return ret;
>> >> +
>> >> + for (mchan_idx = 0; mchan_idx < sba->mchans_count; mchan_idx++)
>> >> + mbox_client_peek_data(sba->mchans[mchan_idx]);
>> >
>> > what is this achieving?
>>
>> The mbox_client_peek_data() is a hint to mailbox controller driver
>> to check for available messages.
>>
>> This gives good performance improvement when some DMA client
>> code is polling using tx_status() callback.
>
> Then why do it before and then check status.
If there was a work completed when mbox_client_peek_data()
is called then sba_receive_message() will be called immediately
by mailbox controller driver.
We are doing dma_cookie_complete() in sba_receive_message()
so if mbox_client_peek_data() is called before dma_cookie_status()
then dma_cookie_status() will see correct state of cookie.
Also, I explored virt-dma APIs for BCM-SBA-RAID driver. The virt-dma
implements tasklet based bottom-half for each virt-dma-channel. This
bottom-half is not required for BCM-FS4-RAID driver because its a
mailbox client driver and the mailbox controller driver already implements
bottom-half for each mailbox channel.
If we still go ahead and use virt-dma in BCM-FS4-RAID driver then we
will have two bottom-halfs in-action one in mailbox controller driver and
another in BCM-FS4-RAID driver which in-turn will add bottom-half
scheduling overhead thereby reducing performance of BCM-FS4-RAID
driver.
Regards,
Anup
next prev parent reply other threads:[~2017-02-07 6:02 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-02-02 4:47 [PATCH 0/6] Broadcom SBA RAID support Anup Patel
2017-02-02 4:47 ` [PATCH 1/6] mailbox: Add new API mbox_channel_device() for clients Anup Patel
2017-02-03 12:05 ` Jassi Brar
2017-02-06 4:27 ` Anup Patel
2017-02-02 4:47 ` [PATCH 2/6] lib/raid6: Add log-of-2 table for RAID6 HW requiring disk position Anup Patel
2017-02-02 4:47 ` [PATCH 3/6] async_tx: Handle DMA devices having support for fewer PQ coefficients Anup Patel
2017-02-02 6:01 ` Dan Williams
2017-02-03 11:00 ` Anup Patel
[not found] ` <CAALAos8HEjPhdM0cibTVB==WsanktBx87e8b8diVsNm1EmCQHQ@mail.gmail.com>
[not found] ` <CAALAos8HEjPhdM0cibTVB==WsanktBx87e8b8diVsNm1EmCQHQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-02-03 18:42 ` Dan Williams
2017-02-06 3:55 ` Anup Patel
2017-02-02 4:47 ` [PATCH 4/6] async_tx: Fix DMA_PREP_FENCE usage in do_async_gen_syndrome() Anup Patel
2017-02-02 4:47 ` [PATCH 5/6] dmaengine: Add Broadcom SBA RAID driver Anup Patel
[not found] ` <1486010836-25228-6-git-send-email-anup.patel-dY08KVG/lbpWk0Htik3J/w@public.gmane.org>
2017-02-05 6:06 ` Vinod Koul
2017-02-06 12:01 ` Anup Patel
2017-02-06 16:54 ` Vinod Koul
2017-02-07 6:02 ` Anup Patel [this message]
[not found] ` <1486010836-25228-1-git-send-email-anup.patel-dY08KVG/lbpWk0Htik3J/w@public.gmane.org>
2017-02-02 4:47 ` [PATCH 6/6] dt-bindings: Add DT bindings document for " Anup Patel
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