linux-kernel - Re: [PATCH 1/2] mtd: rawnand: qcom: Pass 18 bit offset from QPIC base address to BAM

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Message-ID: <e76e9562-f7d0-88c9-dcb6-dfcf41cdf205@quicinc.com>
Date: Thu, 21 Nov 2024 11:33:13 +0530
From: Md Sadre Alam <quic_mdalam@...cinc.com>
To: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
CC: <miquel.raynal@...tlin.com>, <richard@....at>, <vigneshr@...com>,
        <linux-mtd@...ts.infradead.org>, <linux-arm-msm@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <quic_srichara@...cinc.com>,
        <quic_nainmeht@...cinc.com>, <quic_laksd@...cinc.com>,
        <quic_varada@...cinc.com>
Subject: Re: [PATCH 1/2] mtd: rawnand: qcom: Pass 18 bit offset from QPIC base
 address to BAM



On 11/20/2024 12:31 PM, Manivannan Sadhasivam wrote:
> On Tue, Nov 19, 2024 at 02:50:57PM +0530, Md Sadre Alam wrote:
>> Currently we are configuring lower 24 bits of address in descriptor
>> whereas QPIC design expects 18 bit register offset from QPIC base
> 
> You mean 'QPIC IP' here? But is it QPIC or NANDc? I guess the later.
It's QPIC IP only.
> 
>> address to be configured in cmd descriptors. This is leading to a
>> different address actually being used in HW, leading to wrong value
>> read.
>>
> 
> This doesn't clearly say what the actual issue is. IIUC, the issue is that the
> NANDc base address is different from the QPIC base address. But the driver
> doesn't take it into account and just used the QPIC base as the NANDc base. This
> used to work as the NANDc IP only considers the lower 18 bits of the address
> passed by the driver to derive the register offset. Since the base address of
> QPIC used to contain all 0 for lower 18 bits (like 0x07980000), the driver ended
> up passing the actual register offset in it and NANDc worked properly. But on
> newer SoCs like SDX75, the QPIC base address doesn't contain all 0 for lower 18
> bits (like 0x01C98000). So NANDc sees wrong offset as per the current logic.
Yes correct. If QPIC address = 0x07980000 and QPIC_EBI2NAND address = 0x079b0000
the the diff is 0x30000, this is the actual offset expected by QPIC RTL code.
and RTL needs only 18-bit offset.
> 
>> Older targets also used same configuration (lower 24 bits) like sdxpinn,
> 
> Please use actual product names and not internal names. I believe you are
> referring to SDX55/SDX65 here.
Ok , will change in next revision.
> 
>> ipq etc. but issue is masked in older targets due to lower 18 bits of QPIC
>> base address being zero leading to expected address generation.
>>
>> Sdxpinn     : QPIC_QPIC | 0x01C98000 (Lower 18 bits are non zero)
>> Sdxnightjar : QPIC_QPIC | 0x07980000 (Lower 18 bits are zero) Same for
>> older targets.
> 
> Same here.
Ok
> 
>>
>> Signed-off-by: Md Sadre Alam <quic_mdalam@...cinc.com>
> 
> Please add relevant Fixes tag.
Ok
> 
>> ---
>>   drivers/mtd/nand/raw/qcom_nandc.c | 9 +++++++--
>>   1 file changed, 7 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/mtd/nand/raw/qcom_nandc.c b/drivers/mtd/nand/raw/qcom_nandc.c
>> index b8cff9240b28..34ee8555fb8a 100644
>> --- a/drivers/mtd/nand/raw/qcom_nandc.c
>> +++ b/drivers/mtd/nand/raw/qcom_nandc.c
>> @@ -207,7 +207,7 @@ nandc_set_reg(chip, reg,			\
>>   #define dev_cmd_reg_addr(nandc, reg) ((nandc)->props->dev_cmd_reg_start + (reg))
>>   
>>   /* Returns the NAND register physical address */
>> -#define nandc_reg_phys(chip, offset) ((chip)->base_phys + (offset))
>> +#define nandc_reg_phys(chip, offset)  ((nandc)->props->offset_from_qpic + (offset))
>>   
>>   /* Returns the dma address for reg read buffer */
>>   #define reg_buf_dma_addr(chip, vaddr) \
>> @@ -561,6 +561,7 @@ struct qcom_nandc_props {
>>   	bool is_qpic;
>>   	bool qpic_v2;
>>   	bool use_codeword_fixup;
>> +	u32 offset_from_qpic;
> 
> nandc_offset?
Ok
> 
>>   };
>>   
>>   /* Frees the BAM transaction memory */
>> @@ -3477,6 +3478,7 @@ static const struct qcom_nandc_props ipq806x_nandc_props = {
>>   	.is_bam = false,
>>   	.use_codeword_fixup = true,
>>   	.dev_cmd_reg_start = 0x0,
>> +	.offset_from_qpic = 0x30000,
> 
> How 0x30000 is supposed to work? You said the NANDc ignores lower 18 bits, but
> this has 17th and 18th bits set.
Not this address 0x30000, this the diff b/w QPIC base and EBI2NAND base. The 18-bits we have see
on this address 0x07980000 and this address 0x01C98000.
> 
> - Mani
>