From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jiancheng Xue Subject: Re: [RESEND PATCH v9] mtd: spi-nor: add hisilicon spi-nor flash controller driver Date: Fri, 8 Apr 2016 16:26:14 +0800 Message-ID: <57076B26.7030700@huawei.com> 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> Mime-Version: 1.0 Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <5705C5E2.6070206-ynQEQJNshbs@public.gmane.org> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Marek Vasut , Brian Norris Cc: linux-mtd-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, dwmw2-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org, boris.brezillon-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org, juhosg-p3rKhJxN3npAfugRpC6u6w@public.gmane.org, furquan-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org, suwenping-C8/M+/jPZTeaMJb+Lgu22Q@public.gmane.org, devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, yanhaifeng-C8/M+/jPZTeaMJb+Lgu22Q@public.gmane.org, raojun-C8/M+/jPZTeaMJb+Lgu22Q@public.gmane.org, xuejiancheng-C8/M+/jPZTeaMJb+Lgu22Q@public.gmane.org, ml.yang-C8/M+/jPZTeaMJb+Lgu22Q@public.gmane.org, gaofei-C8/M+/jPZTeaMJb+Lgu22Q@public.gmane.org, yanghongwei-C8/M+/jPZTeaMJb+Lgu22Q@public.gmane.org, zhangzhenxing-C8/M+/jPZTeaMJb+Lgu22Q@public.gmane.org List-Id: devicetree@vger.kernel.org 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! Regards, Jiancheng >> } else { >> /* read HIFMC_DMA_MAX_LEN bytes at a time */ >> for (i = 0; i < len; i += HIFMC_DMA_MAX_LEN) { >> hisi_spi_nor_dma_transfer(nor, from + i, host->dma_buffer, >> HIFMC_DMA_MAX_LEN, FMC_OP_READ); >> memcpy(read_buf + i, host->buffer, HIFMC_DMA_MAX_LEN); >> } >> /* read remaining bytes */ >> i -= HIFMC_DMA_MAX_LEN; >> hisi_spi_nor_dma_transfer(nor, from + i, host->dma_buffer, >> len - i, FMC_OP_READ); >> memcpy(read_buf + i, host->buffer, len - i); >> } >> *retlen = len; >> >> return 0; >> } >> [...] >> On 2016/4/4 14:44, Brian Norris wrote: >>> Hi Jiancheng, >>> >>> Looking good. In addition to Marek's comments, I have just a few small >>> comments. I'll post a small diff at the end, and a few inline comments. >>> > > -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html