Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755346AbdGXQgs (ORCPT ); Mon, 24 Jul 2017 12:36:48 -0400 Received: from mail-wm0-f49.google.com ([74.125.82.49]:38425 "EHLO mail-wm0-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753404AbdGXQgl (ORCPT ); Mon, 24 Jul 2017 12:36:41 -0400 MIME-Version: 1.0 In-Reply-To: References: <1500620142-910-1-git-send-email-anup.patel@broadcom.com> <1500620142-910-7-git-send-email-anup.patel@broadcom.com> From: Jassi Brar Date: Mon, 24 Jul 2017 22:06:39 +0530 Message-ID: Subject: Re: [PATCH v2 6/7] mailbox: bcm-flexrm-mailbox: Set msg_queue_len for each channel To: Anup Patel Cc: Rob Herring , Mark Rutland , Catalin Marinas , Will Deacon , Florian Fainelli , Scott Branden , Ray Jui , Linux Kernel Mailing List , "linux-arm-kernel@lists.infradead.org" , Devicetree List , BCM Kernel Feedback Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2894 Lines: 62 On Mon, Jul 24, 2017 at 9:26 AM, Anup Patel wrote: > Hi Jassi, > > Sorry for the delayed response... > > On Fri, Jul 21, 2017 at 9:16 PM, Jassi Brar wrote: >> Hi Anup, >> >> On Fri, Jul 21, 2017 at 12:25 PM, Anup Patel wrote: >>> The Broadcom FlexRM ring (i.e. mailbox channel) can handle >>> larger number of messages queued in one FlexRM ring hence >>> this patch sets msg_queue_len for each mailbox channel to >>> be same as RING_MAX_REQ_COUNT. >>> >>> Signed-off-by: Anup Patel >>> Reviewed-by: Scott Branden >>> --- >>> drivers/mailbox/bcm-flexrm-mailbox.c | 5 ++++- >>> 1 file changed, 4 insertions(+), 1 deletion(-) >>> >>> diff --git a/drivers/mailbox/bcm-flexrm-mailbox.c b/drivers/mailbox/bcm-flexrm-mailbox.c >>> index 9873818..20055a0 100644 >>> --- a/drivers/mailbox/bcm-flexrm-mailbox.c >>> +++ b/drivers/mailbox/bcm-flexrm-mailbox.c >>> @@ -1683,8 +1683,11 @@ static int flexrm_mbox_probe(struct platform_device *pdev) >>> ret = -ENOMEM; >>> goto fail_free_debugfs_root; >>> } >>> - for (index = 0; index < mbox->num_rings; index++) >>> + for (index = 0; index < mbox->num_rings; index++) { >>> + mbox->controller.chans[index].msg_queue_len = >>> + RING_MAX_REQ_COUNT; >>> mbox->controller.chans[index].con_priv = &mbox->rings[index]; >>> + } >>> >> While writing mailbox.c I wasn't unaware that there is the option to >> choose the queue length at runtime. >> The idea was to keep the code as simple as possible. I am open to >> making it a runtime thing, but first, please help me understand how >> that is useful here. >> >> I understand FlexRm has a ring buffer of RING_MAX_REQ_COUNT(1024) >> elements. Any message submitted to mailbox api can be immediately >> written onto the ringbuffer if there is some space. >> Is there any mechanism to report back to a client driver, if its >> message in ringbuffer failed "to be sent"? >> If there isn't any, then I think, in flexrm_last_tx_done() you should >> simply return true if there is some space left in the rung-buffer, >> false otherwise. > > Yes, we have error code in "struct brcm_message" to report back > errors from send_message. In our mailbox clients, we check > return value of mbox_send_message() and also the error code > in "struct brcm_message". > I meant after the message has been accepted in the ringbuffer but the remote failed to receive it. There seems no such provision. IIANW, then you should be able to consider every message as "sent successfully" once it is in the ring buffer i.e, immediately after mbox_send_message() returns 0. In that case I would think you don't need more than a couple of entries out of MBOX_TX_QUEUE_LEN ?