From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jaehoon Chung Subject: Re: [PATCH] Revert "mmc: dw_mmc: Add check for IDMAC configuration" Date: Tue, 11 Sep 2012 13:36:26 +0900 Message-ID: <504EBFCA.3080203@samsung.com> References: <00d801cd8fc4$738f8540$5aae8fc0$%jun@samsung.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: Received: from mailout2.samsung.com ([203.254.224.25]:12206 "EHLO mailout2.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750736Ab2IKEgi (ORCPT ); Tue, 11 Sep 2012 00:36:38 -0400 Received: from epcpsbgm2.samsung.com (epcpsbgm2 [203.254.230.27]) by mailout2.samsung.com (Oracle Communications Messaging Server 7u4-24.01(7.0.4.24.0) 64bit (built Nov 17 2011)) with ESMTP id <0MA6009IU4SKQH10@mailout2.samsung.com> for linux-mmc@vger.kernel.org; Tue, 11 Sep 2012 13:36:29 +0900 (KST) Received: from [10.90.51.55] by mmp2.samsung.com (Oracle Communications Messaging Server 7u4-24.01(7.0.4.24.0) 64bit (built Nov 17 2011)) with ESMTPA id <0MA60028C4SSPJK0@mmp2.samsung.com> for linux-mmc@vger.kernel.org; Tue, 11 Sep 2012 13:36:29 +0900 (KST) In-reply-to: Sender: linux-mmc-owner@vger.kernel.org List-Id: linux-mmc@vger.kernel.org To: Girish K S Cc: Seungwon Jeon , linux-mmc@vger.kernel.org, cjb@laptop.org, will.newton@imgtec.com, James Hogan On 09/11/2012 12:46 PM, Girish K S wrote: > On 11 September 2012 07:53, Seungwon Jeon wrote: >> This reverts commit 94c6cee91(Add check for IDMAC configuration). >> Synopsys says that only if internal dmac is not present, optional >> external dma interface is present. When internal dmac is present, >> '0' value in DMA_INTERFACE of HCON is reasonable. DMA_INTERFACE >> indicates external dma interface. And idmac initialization is >> prohibited now. So, let's revert this commit. > > There is no register, or a field in any register which says IDMAC present. > I can see only use_idmac bit field in CTRL register. > So in first place how will i know whether IDMAC is present? Have you > assumed that IDMAC is present. > I would like to know without assuming, whether IDMAC is present. > If i have missed out something let me know. i will check and revert back I understood that if INTERNAL_DMAC at HCON register is set to 1, we didn't consdier the DMA_INTERFACE's value. So although dma_interface is set to 0 or others, host can use the internal DMA. Best Regards, Jaehoon Chung > >> >> CC: Girish K S >> Signed-off-by: Seungwon Jeon >> --- >> drivers/mmc/host/dw_mmc.c | 15 ++------------- >> 1 files changed, 2 insertions(+), 13 deletions(-) >> >> diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c >> index 36f98c0..dcbe9aa 100644 >> --- a/drivers/mmc/host/dw_mmc.c >> +++ b/drivers/mmc/host/dw_mmc.c >> @@ -405,23 +405,11 @@ static void dw_mci_idmac_start_dma(struct dw_mci *host, unsigned int sg_len) >> static int dw_mci_idmac_init(struct dw_mci *host) >> { >> struct idmac_desc *p; >> - int i, dma_support; >> + int i; >> >> /* Number of descriptors in the ring buffer */ >> host->ring_size = PAGE_SIZE / sizeof(struct idmac_desc); >> >> - /* Check if Hardware Configuration Register has support for DMA */ >> - dma_support = (mci_readl(host, HCON) >> 16) & 0x3; >> - >> - if (!dma_support || dma_support > 2) { >> - dev_err(&host->dev, >> - "Host Controller does not support IDMA Tx.\n"); >> - host->dma_ops = NULL; >> - return -ENODEV; >> - } >> - >> - dev_info(&host->dev, "Using internal DMA controller.\n"); >> - >> /* Forward link the descriptor list */ >> for (i = 0, p = host->sg_cpu; i < host->ring_size - 1; i++, p++) >> p->des3 = host->sg_dma + (sizeof(struct idmac_desc) * (i + 1)); >> @@ -1895,6 +1883,7 @@ static void dw_mci_init_dma(struct dw_mci *host) >> /* Determine which DMA interface to use */ >> #ifdef CONFIG_MMC_DW_IDMAC >> host->dma_ops = &dw_mci_idmac_ops; >> + dev_info(&host->dev, "Using internal DMA controller.\n"); >> #endif >> >> if (!host->dma_ops) >> -- >> 1.7.0.4 >> >> > -- > To unsubscribe from this list: send the line "unsubscribe linux-mmc" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >