From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Gupta, Pekon" To: Lee Jones , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" Subject: RE: [RFC 23/47] mtd: nand: stm_nand_bch: read and write page (BCH) 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> Content-Language: en-US Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Cc: "dwmw2@infradead.org" , "computersforpeace@gmail.com" , "linux-mtd@lists.infradead.org" , "kernel@stlinux.com" , "angus.clark@st.com" List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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_b= ch.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 =3D &bch_prog_read_page; >+ uint32_t page_size =3D nandi->info.mtd.writesize; >+ unsigned long list_phys; >+ unsigned long buf_phys; >+ uint32_t ecc_err; >+ int ret =3D 0; >+ >+ dev_dbg(nandi->dev, "%s: offs =3D 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 =3D (uint32_t)((offs >> (nandi->page_shift - 8)) & 0xffffff00= ); >+ >+ buf_phys =3D dma_map_single(NULL, buf, page_size, DMA_FROM_DEVICE); >+ >+ memset(nandi->buf_list, 0x00, NANDI_BCH_BUF_LIST_SIZE); >+ nandi->buf_list[0] =3D buf_phys | (nandi->sectors_per_page - 1); >+ >+ list_phys =3D 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_pa= ge(). 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 lim= itation ? 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 =3D readl(nandi->base + NANDBCH_ECC_SCORE_REG_A) & 0xff; >+ if (ecc_err =3D=3D 0xff) { >+ /* >+ * Downgrade uncorrectable ECC error for an erased page, >+ * tolerating 'sectors_per_page' bits at zero. >+ */ >+ ret =3D check_erased_page(buf, page_size, >+ nandi->sectors_per_page); This is also not correct. Here 'max_zeros' should be ecc.strength >+ if (ret >=3D 0) >+ dev_dbg(nandi->dev, >+ "%s: erased page detected: \n" >+ " downgrading uncorrectable ECC error.\n", >+ __func__); >+ } else { >+ ret =3D (int)ecc_err; >+ } >+ >+ return ret; >+} >+ with regards, pekon