Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758643Ab1FWDB3 (ORCPT ); Wed, 22 Jun 2011 23:01:29 -0400 Received: from mail-pw0-f46.google.com ([209.85.160.46]:63754 "EHLO mail-pw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757061Ab1FWDB2 (ORCPT ); Wed, 22 Jun 2011 23:01:28 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:user-agent:mime-version:to:cc:subject :references:in-reply-to:content-type:content-transfer-encoding; b=B9WrW9lBazML7cyGkKlt/QlL4BZ6mbr5/rootbmOH5q3dJW9KtjfNbxpYwToWKGzdG KOr1QeWe2+fQSBuOjXVV9h6VShbCpI1Sk6xLfUfcfuol7vut1uVPBslxhrzRFFGSRh6X bOIpERDcZCcPUoFSudiIxtQrEr75YhMjz6JzI= Message-ID: <4E02AC85.90300@gmail.com> Date: Wed, 22 Jun 2011 20:01:25 -0700 From: Dirk Brandewie User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.17) Gecko/20110428 Fedora/3.1.10-1.fc13 Thunderbird/3.1.10 MIME-Version: 1.0 To: Feng Tang CC: "linux-kernel@vger.kernel.org" , "spi-devel-general@lists.sourceforge.net" Subject: Re: [PATCH 08/11] spi-dw: Ensure fifo lenght is set. References: <1308794413-11069-1-git-send-email-dirk.brandewie@gmail.com> <1308794413-11069-9-git-send-email-dirk.brandewie@gmail.com> <20110623104144.024cc955@feng-i7> In-Reply-To: <20110623104144.024cc955@feng-i7> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2674 Lines: 77 On 06/22/2011 07:41 PM, Feng Tang wrote: > > > On Thu, 23 Jun 2011 10:00:10 +0800 > "dirk.brandewie@gmail.com" wrote: > >> From: Dirk Brandewie >> >> Bug on fifo_len not being set. The fifo sizing routine does not work >> since the txfltr register can not be written while the controller is >> enabled. The max value of txfltr can be larger than the fifo. The >> register allows values upto 0x3f (63) the fifo depth on the Intel >> SOC's if 40 >> >> Signed-off-by: Dirk Brandewie >> --- >> drivers/spi/spi-dw.c | 18 ++---------------- >> 1 files changed, 2 insertions(+), 16 deletions(-) >> >> diff --git a/drivers/spi/spi-dw.c b/drivers/spi/spi-dw.c >> index ad92826..cc38aa0 100644 >> --- a/drivers/spi/spi-dw.c >> +++ b/drivers/spi/spi-dw.c >> @@ -776,25 +776,11 @@ static int destroy_queue(struct spi_dw *dws) >> /* Restart the controller, disable all interrupts, clean rx fifo */ >> static void spi_dw_hw_init(struct spi_dw *dws) >> { >> + BUG_ON(!dws->fifo_len); >> + >> spi_dw_disable(dws); >> spi_dw_mask_intr(dws, 0xff); >> spi_dw_enable(dws); >> - >> - /* >> - * Try to detect the FIFO depth if not set by interface >> driver, >> - * the depth could be from 2 to 256 from HW spec >> - */ >> - if (!dws->fifo_len) { >> - u32 fifo; >> - for (fifo = 2; fifo<= 257; fifo++) { >> - dw_writew(dws, txfltr, fifo); >> - if (fifo != dw_readw(dws, txfltr)) >> - break; >> - } >> - >> - dws->fifo_len = (fifo == 257) ? 0 : fifo; >> - dw_writew(dws, txfltr, 0); >> - } >> } > > This code is requested by other community developers, the FIFO > length is adjustable for the dw_spi core when deployed on > different platforms, for those who are not certain about the > FIFO len, they can use this code to probe the FIFO len. > > So we need to keep it. > Then I have bad documentation because document I have says that you can NOt write to txfltr while the controller is enabled. The sizing routine as it stands can't work for the implementation in Moorsetown and Medfield. If there are other SOC's that are implementing different semantics for txfltr we will need to handle this differently and do some runtime detection of how the fifo should be sized. Can you give ne a reference to the person that requiested the sizing code so I can follow-up >> >> int __devinit spi_dw_add_host(struct spi_dw *dws) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/