From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-out.m-online.net ([212.18.0.9]) by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1aphbj-0002uj-0b for linux-mtd@lists.infradead.org; Mon, 11 Apr 2016 19:34:48 +0000 Message-ID: <570BF933.2000607@denx.de> Date: Mon, 11 Apr 2016 21:21:23 +0200 From: Marek Vasut MIME-Version: 1.0 To: Jiancheng Xue , Brian Norris CC: linux-mtd@lists.infradead.org, robh+dt@kernel.org, dwmw2@infradead.org, boris.brezillon@free-electrons.com, juhosg@openwrt.org, furquan@google.com, suwenping@hisilicon.com, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, yanhaifeng@hisilicon.com, raojun@hisilicon.com, xuejiancheng@hisilicon.com, ml.yang@hisilicon.com, gaofei@hisilicon.com, yanghongwei@hisilicon.com, zhangzhenxing@hisilicon.com Subject: Re: [RESEND PATCH v9] mtd: spi-nor: add hisilicon spi-nor flash controller driver References: <1458979861-3619-1-git-send-email-xuejiancheng@huawei.com> <56F73BC9.5000300@gmail.com> <56F8F630.5050008@huawei.com> <20160404064418.GC13995@localhost> <5705C17F.9030904@huawei.com> <5705C5E2.6070206@denx.de> <57076B26.7030700@huawei.com> <5707821F.4020300@denx.de> <570AFDAF.9050607@huawei.com> In-Reply-To: <570AFDAF.9050607@huawei.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On 04/11/2016 03:28 AM, Jiancheng Xue wrote: > Hi, > > On 2016/4/8 18:04, Marek Vasut wrote: >> On 04/08/2016 10:26 AM, Jiancheng Xue wrote: >>> Hi, >>> >>> On 2016/4/7 10:28, Marek Vasut wrote: >>>> On 04/07/2016 04:10 AM, Jiancheng Xue wrote: >>>>> Hi Brian, >>>>> Thank you very much for your comments. I'll fix these issues in next version. >>>>> In addition, for easy understanding I'd like to rewrite hisi_spi_nor_write and >>>>> hisi_spi_nor_read. Your comments on these modifications will be highly appreciated. >>>> >>>> Would you please stop top-posting ? It rubs some people the wrong way. >>>> >>> I feel very sorry about that. I have read the etiquette and won't make the same mistake again. >>> >>>>> static int hisi_spi_nor_read(struct spi_nor *nor, loff_t from, size_t len, >>>>> size_t *retlen, u_char *read_buf) >>>>> { >>>>> struct hifmc_priv *priv = nor->priv; >>>>> struct hifmc_host *host = priv->host; >>>>> int i; >>>>> >>>>> /* read all bytes in only one time */ >>>>> if (len <= HIFMC_DMA_MAX_LEN) { >>>>> hisi_spi_nor_dma_transfer(nor, from, host->dma_buffer, >>>>> len, FMC_OP_READ); >>>>> memcpy(read_buf, host->buffer, len); >>>> >>>> Is all the ad-hoc memcpying necessary? I think you can use >>>> dma_map_single() and co to obtain DMAble memory for your >>>> controller's use and then you can probably get rid of most >>>> of this stuff. >>>> >>> Considering read_buf >= high_mem case, I think it is also complicated to use dma_map_* >>> and the DMA buffer allocated by the driver is still needed. But I am not sure about >>> this. Please let me know if I am wrong. Thank you! >> >> Does your controller/DMA have a limitation where it's buffers must be in >> the bottom 4GiB range ? The DMA framework should be able to take care of >> such platform limitations. >> > When read_buf is allocated by vmalloc, the underlying physical memory may be not contiguous. > In this case, dma_map_single can't be used directly. I think inner DMA buffer and memcpy are still > needed. Am I right? Take a look at drivers/spi/spi-mxs.c , look for "vmalloc" , does that solution help you in any way ? -- Best regards, Marek Vasut