From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753819AbaCZKRw (ORCPT ); Wed, 26 Mar 2014 06:17:52 -0400 Received: from arroyo.ext.ti.com ([192.94.94.40]:46651 "EHLO arroyo.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750792AbaCZKRu convert rfc822-to-8bit (ORCPT ); Wed, 26 Mar 2014 06:17:50 -0400 From: "Gupta, Pekon" To: Lee Jones , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" CC: "kernel@stlinux.com" , "computersforpeace@gmail.com" , "linux-mtd@lists.infradead.org" , "dwmw2@infradead.org" , "angus.clark@st.com" Subject: RE: [RFC 23/47] mtd: nand: stm_nand_bch: read and write page (BCH) Thread-Topic: [RFC 23/47] mtd: nand: stm_nand_bch: read and write page (BCH) Thread-Index: AQHPSAMr05odAmsliUqmk9LWSNZ4qprzJb7Q Date: Wed, 26 Mar 2014 10:17:08 +0000 Message-ID: <20980858CB6D3A4BAE95CA194937D5E73EAB5CAC@DBDE04.ent.ti.com> References: <1395735604-26706-1-git-send-email-lee.jones@linaro.org> <1395735604-26706-24-git-send-email-lee.jones@linaro.org> In-Reply-To: <1395735604-26706-24-git-send-email-lee.jones@linaro.org> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [172.24.170.142] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Lee, >From: Lee Jones [mailto:lee.jones@linaro.org] > >Use DMA to read and/or write a single page of data. > >Signed-off-by: Lee Jones >--- > drivers/mtd/nand/stm_nand_bch.c | 119 ++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 119 insertions(+) > >diff --git a/drivers/mtd/nand/stm_nand_bch.c b/drivers/mtd/nand/stm_nand_bch.c >index 7874d85..6323590 100644 >--- a/drivers/mtd/nand/stm_nand_bch.c >+++ b/drivers/mtd/nand/stm_nand_bch.c >@@ -21,6 +21,7 @@ > #include > #include > #include >+#include > #include > #include > #include >@@ -345,6 +346,124 @@ static int check_erased_page(uint8_t *data, uint32_t page_size, int max_zeros) > return zeros; > } > >+/* Returns the number of ECC errors, or '-1' for uncorrectable error */ >+static int bch_read_page(struct nandi_controller *nandi, >+ loff_t offs, >+ uint8_t *buf) >+{ >+ struct bch_prog *prog = &bch_prog_read_page; >+ uint32_t page_size = nandi->info.mtd.writesize; >+ unsigned long list_phys; >+ unsigned long buf_phys; >+ uint32_t ecc_err; >+ int ret = 0; >+ >+ dev_dbg(nandi->dev, "%s: offs = 0x%012llx\n", __func__, offs); >+ >+ BUG_ON((unsigned long)buf & (NANDI_BCH_DMA_ALIGNMENT - 1)); >+ BUG_ON(offs & (NANDI_BCH_DMA_ALIGNMENT - 1)); >+ >+ emiss_nandi_select(STM_NANDI_BCH); >+ >+ nandi_enable_interrupts(nandi, NANDBCH_INT_SEQNODESOVER); >+ reinit_completion(&nandi->seq_completed); >+ >+ /* Reset ECC stats */ >+ writel(CFG_RESET_ECC_ALL | CFG_ENABLE_AFM, >+ nandi->base + NANDBCH_CONTROLLER_CFG); >+ writel(CFG_ENABLE_AFM, nandi->base + NANDBCH_CONTROLLER_CFG); >+ >+ prog->addr = (uint32_t)((offs >> (nandi->page_shift - 8)) & 0xffffff00); >+ >+ buf_phys = dma_map_single(NULL, buf, page_size, DMA_FROM_DEVICE); >+ >+ memset(nandi->buf_list, 0x00, NANDI_BCH_BUF_LIST_SIZE); >+ nandi->buf_list[0] = buf_phys | (nandi->sectors_per_page - 1); >+ >+ list_phys = dma_map_single(NULL, nandi->buf_list, >+ NANDI_BCH_BUF_LIST_SIZE, DMA_TO_DEVICE); >+ >+ writel(list_phys, nandi->base + NANDBCH_BUFFER_LIST_PTR); >+ >+ bch_load_prog_cpu(nandi, prog); >+ >+ bch_wait_seq(nandi); >+ >+ nandi_disable_interrupts(nandi, NANDBCH_INT_SEQNODESOVER); >+ >+ dma_unmap_single(NULL, list_phys, NANDI_BCH_BUF_LIST_SIZE, >+ DMA_TO_DEVICE); >+ dma_unmap_single(NULL, buf_phys, page_size, DMA_FROM_DEVICE); >+ >+ /* Use the maximum per-sector ECC count! */ Firstly, this ecc checking and correction should not be part of bch_read_page(). This should be part of chip->ecc.correct(). But, I don't see your driver using nand_chip->ecc interfaces. Why do you want to break away from generic driver flow ? any controller limitation ? I think much of the code in below patch can be reused from nand_base.c [RFC 43/47] mtd: nand: stm_nand_bch: read and write functions (BCH) >+ ecc_err = readl(nandi->base + NANDBCH_ECC_SCORE_REG_A) & 0xff; >+ if (ecc_err == 0xff) { >+ /* >+ * Downgrade uncorrectable ECC error for an erased page, >+ * tolerating 'sectors_per_page' bits at zero. >+ */ >+ ret = check_erased_page(buf, page_size, >+ nandi->sectors_per_page); This is also not correct. Here 'max_zeros' should be ecc.strength >+ if (ret >= 0) >+ dev_dbg(nandi->dev, >+ "%s: erased page detected: \n" >+ " downgrading uncorrectable ECC error.\n", >+ __func__); >+ } else { >+ ret = (int)ecc_err; >+ } >+ >+ return ret; >+} >+ with regards, pekon