From: mathias.nyman@linux.intel.com (Mathias Nyman)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v9 4/5] xhci: mediatek: support MTK xHCI host controller
Date: Thu, 08 Oct 2015 16:05:00 +0300 [thread overview]
Message-ID: <561669FC.3030600@linux.intel.com> (raw)
In-Reply-To: <5616616D.3080205@linaro.org>
On 08.10.2015 15:28, Daniel Thompson wrote:
> On 08/10/15 13:05, chunfeng yun wrote:
>> Hi,
>> On Thu, 2015-10-01 at 12:44 +0100, Daniel Thompson wrote:
>>> On 29/09/15 04:01, Chunfeng Yun wrote:
>>>> There some vendor quirks for MTK xhci host controller:
>>>> 1. It defines some extra SW scheduling parameters for HW
>>>> to minimize the scheduling effort for synchronous and
>>>> interrupt endpoints. The parameters are put into reseved
>>>> DWs of slot context and endpoint context.
>>>> 2. Its IMODI unit for Interrupter Moderation register is
>>>> 8 times as much as that defined in xHCI spec.
>>>> 3. Its TDS in Normal TRB defines a number of packets that
>>>> remains to be transferred for a TD after processing all
>>>> Max packets in all previous TRBs.
>>>>
>>>> Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
>>>
>>> I've done some basic soak tests, both with a directly attached USB3 HDD
>>> and, given the extra code to manage isochronous xfer, also with a hub,
>>> disc and two audio interfaces.
>>>
>>> Tested-by: Daniel Thompson <daniel.thompson@linaro.org>
>>>
>>>
>>>> diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
>>>> index 57f40a1..243f696 100644
>>>> --- a/drivers/usb/host/xhci-ring.c
>>>> +++ b/drivers/usb/host/xhci-ring.c
>>>> @@ -68,6 +68,7 @@
>>>> #include <linux/slab.h>
>>>> #include "xhci.h"
>>>> #include "xhci-trace.h"
>>>> +#include "xhci-mtk.h"
>>>>
>>>> /*
>>>> * Returns zero if the TRB isn't in this segment, otherwise it returns the DMA
>>>> @@ -3044,18 +3045,27 @@ static u32 xhci_td_remainder(struct xhci_hcd *xhci, int transferred,
>>>> struct urb *urb, unsigned int num_trbs_left)
>>>> {
>>>> u32 maxp, total_packet_count;
>>>> + u32 skip_current_trb = 0;
>>>
>>> A bit of a nitpick but why do we need skip_current_trb? Testing
>>> (xhci->quirks & XHCI_MTK_HOST) twice would make what the code does, and
>>> why, more obvious.
>>>
>> I am not sure which way it is better, so add variable of
>> skip_current_trb to reduce test times.
>
> I can't imagine either approach impacts performance. However introducing skip_current_trb makes the flow of the branches harder to follow.
>
> The first branch was a version check and can remain so; we only need to do something special with the quirks because the MTK controller is 0.97 but with a few bits added:
>
> /* MTK xHCI is mostly 0.97 but contains some features from 1.0 */
> if (xhci->hci_version < 0x100 && !(xhci->quirks & XHCI_MTK_HOST))
> return ...
>
> Setting trb_buff_len to zero is accommodating a quirk and this is clearer when we have:
>
> /* for MTK xHCI, TD size doesn't include this TRB */
> if (xhci->quirks & XHCI_MTK_HOST)
> trb_buff_len = 0;
Both will work, but I'd prefer this solution as well.
-Mathias
next prev parent reply other threads:[~2015-10-08 13:05 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-09-29 3:01 [PATCH v9 0/5] Mediatek xHCI support Chunfeng Yun
2015-09-29 3:01 ` [PATCH v9 1/5] dt-bindings: Add usb3.0 phy binding for MT65xx SoCs Chunfeng Yun
2015-09-29 14:43 ` Sergei Shtylyov
2015-10-08 11:27 ` chunfeng yun
2015-09-29 3:01 ` [PATCH v9 2/5] dt-bindings: Add a binding for Mediatek xHCI host controller Chunfeng Yun
2015-09-29 14:49 ` Sergei Shtylyov
2015-10-08 11:37 ` chunfeng yun
2015-09-29 3:01 ` [PATCH v9 3/5] phy: add usb3.0 phy driver for mt65xx SoCs Chunfeng Yun
2015-10-06 14:20 ` Kishon Vijay Abraham I
2015-10-08 11:45 ` chunfeng yun
2015-09-29 3:01 ` [PATCH v9 4/5] xhci: mediatek: support MTK xHCI host controller Chunfeng Yun
2015-10-01 11:44 ` Daniel Thompson
2015-10-08 12:05 ` chunfeng yun
2015-10-08 12:28 ` Daniel Thompson
2015-10-08 13:05 ` Mathias Nyman [this message]
2015-10-08 14:42 ` chunfeng yun
2015-10-08 14:38 ` chunfeng yun
2015-10-15 14:46 ` Mathias Nyman
2015-10-18 1:25 ` chunfeng yun
2015-10-19 11:25 ` Mathias Nyman
2015-10-20 6:29 ` chunfeng yun
2015-10-20 8:25 ` Mathias Nyman
2015-09-29 3:01 ` [PATCH v9 5/5] arm64: dts: mediatek: add xHCI & usb phy for mt8173 Chunfeng Yun
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